[X86] logical AND and OR in if-conditionals can turn to multiple branch instructions #162041

manik-muk · 2025-10-06T04:47:01Z

github-actions · 2025-10-06T04:47:22Z

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llvmbot · 2025-10-06T04:47:51Z

@llvm/pr-subscribers-backend-x86

Author: None (manik-muk)

Changes

Addresses #160612

Full diff: https://github.com/llvm/llvm-project/pull/162041.diff

5 Files Affected:

(modified) llvm/lib/Target/X86/X86ISelLowering.cpp (+18)
(modified) llvm/test/CodeGen/X86/2007-08-09-IllegalX86-64Asm.ll (+53-56)
(added) llvm/test/CodeGen/X86/issue-160612.c (+19)
(added) llvm/test/CodeGen/X86/issue-160612.ll (+74)
(modified) llvm/test/CodeGen/X86/x86-shrink-wrap-unwind.ll (+36-40)

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index cdc97faf394ca..997d04b3ccbe6 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -3625,6 +3625,24 @@ X86TargetLowering::getJumpConditionMergingParams(Instruction::BinaryOps Opc,
       match(Lhs, m_SpecificICmp(ICmpInst::ICMP_EQ, m_Value(), m_Value())) &&
       match(Rhs, m_SpecificICmp(ICmpInst::ICMP_EQ, m_Value(), m_Value())))
     BaseCost += 1;
+  
+  // For OR conditions with EQ comparisons, prefer splitting into branches
+  // (unless CCMP is available). OR+EQ cannot be optimized via bitwise ops,
+  // unlike OR+NE which becomes (P|Q)!=0. Similarly, don't split signed
+  // comparisons (SLT, SGT) that can be optimized.
+  if (BaseCost >= 0 && !Subtarget.hasCCMP() && Opc == Instruction::Or) {
+    auto *LCmp = dyn_cast<ICmpInst>(Lhs);
+    auto *RCmp = dyn_cast<ICmpInst>(Rhs);
+    if (LCmp && RCmp) {
+      ICmpInst::Predicate LPred = LCmp->getPredicate();
+      ICmpInst::Predicate RPred = RCmp->getPredicate();
+      // Split OR+EQ patterns as they don't have clever optimizations
+      if (LPred == ICmpInst::ICMP_EQ && RPred == ICmpInst::ICMP_EQ) {
+        return {-1, -1, -1};
+      }
+    }
+  }
+  
   return {BaseCost, BrMergingLikelyBias.getValue(),
           BrMergingUnlikelyBias.getValue()};
 }
diff --git a/llvm/test/CodeGen/X86/2007-08-09-IllegalX86-64Asm.ll b/llvm/test/CodeGen/X86/2007-08-09-IllegalX86-64Asm.ll
index 28b4541c1bfc7..7bdc4e19a1cf6 100644
--- a/llvm/test/CodeGen/X86/2007-08-09-IllegalX86-64Asm.ll
+++ b/llvm/test/CodeGen/X86/2007-08-09-IllegalX86-64Asm.ll
@@ -44,7 +44,7 @@ define ptr @ubyte_divmod(ptr %a, ptr %b) {
 ; CHECK-NEXT:    leaq {{[0-9]+}}(%rsp), %rsi
 ; CHECK-NEXT:    callq __ubyte_convert_to_ctype
 ; CHECK-NEXT:    testl %eax, %eax
-; CHECK-NEXT:    js LBB0_6
+; CHECK-NEXT:    js LBB0_4
 ; CHECK-NEXT:  ## %bb.1: ## %cond_next.i
 ; CHECK-NEXT:    leaq {{[0-9]+}}(%rsp), %rsi
 ; CHECK-NEXT:    movq %rbx, %rdi
@@ -53,84 +53,81 @@ define ptr @ubyte_divmod(ptr %a, ptr %b) {
 ; CHECK-NEXT:    sarl $31, %ecx
 ; CHECK-NEXT:    andl %eax, %ecx
 ; CHECK-NEXT:    cmpl $-2, %ecx
-; CHECK-NEXT:    je LBB0_10
+; CHECK-NEXT:    je LBB0_8
 ; CHECK-NEXT:  ## %bb.2: ## %cond_next.i
 ; CHECK-NEXT:    cmpl $-1, %ecx
-; CHECK-NEXT:    jne LBB0_3
-; CHECK-NEXT:  LBB0_8: ## %bb4
+; CHECK-NEXT:    jne LBB0_6
+; CHECK-NEXT:  LBB0_3: ## %bb4
 ; CHECK-NEXT:    movq _PyArray_API@GOTPCREL(%rip), %rax
 ; CHECK-NEXT:    movq (%rax), %rax
 ; CHECK-NEXT:    movq 16(%rax), %rax
-; CHECK-NEXT:    jmp LBB0_9
-; CHECK-NEXT:  LBB0_6: ## %_ubyte_convert2_to_ctypes.exit
+; CHECK-NEXT:    jmp LBB0_10
+; CHECK-NEXT:  LBB0_4: ## %_ubyte_convert2_to_ctypes.exit
 ; CHECK-NEXT:    cmpl $-2, %eax
-; CHECK-NEXT:    je LBB0_10
-; CHECK-NEXT:  ## %bb.7: ## %_ubyte_convert2_to_ctypes.exit
-; CHECK-NEXT:    cmpl $-1, %eax
 ; CHECK-NEXT:    je LBB0_8
-; CHECK-NEXT:  LBB0_3: ## %bb35
+; CHECK-NEXT:  ## %bb.5: ## %_ubyte_convert2_to_ctypes.exit
+; CHECK-NEXT:    cmpl $-1, %eax
+; CHECK-NEXT:    je LBB0_3
+; CHECK-NEXT:  LBB0_6: ## %bb35
 ; CHECK-NEXT:    movq _PyUFunc_API@GOTPCREL(%rip), %r14
 ; CHECK-NEXT:    movq (%r14), %rax
 ; CHECK-NEXT:    callq *216(%rax)
 ; CHECK-NEXT:    movzbl {{[0-9]+}}(%rsp), %edx
 ; CHECK-NEXT:    testb %dl, %dl
-; CHECK-NEXT:    je LBB0_4
-; CHECK-NEXT:  ## %bb.12: ## %cond_false.i
-; CHECK-NEXT:    setne %dil
+; CHECK-NEXT:    je LBB0_11
+; CHECK-NEXT:  ## %bb.7: ## %cond_false.i
 ; CHECK-NEXT:    movzbl {{[0-9]+}}(%rsp), %esi
 ; CHECK-NEXT:    movzbl %sil, %ecx
 ; CHECK-NEXT:    movl %ecx, %eax
 ; CHECK-NEXT:    divb %dl
 ; CHECK-NEXT:    movl %eax, %r15d
 ; CHECK-NEXT:    testb %cl, %cl
-; CHECK-NEXT:    setne %al
-; CHECK-NEXT:    testb %dil, %al
-; CHECK-NEXT:    jne LBB0_5
-; CHECK-NEXT:  LBB0_13: ## %cond_true.i200
-; CHECK-NEXT:    testb %dl, %dl
-; CHECK-NEXT:    jne LBB0_15
-; CHECK-NEXT:  ## %bb.14: ## %cond_true14.i
-; CHECK-NEXT:    movl $4, %edi
-; CHECK-NEXT:    callq _feraiseexcept
-; CHECK-NEXT:  LBB0_15: ## %ubyte_ctype_remainder.exit
-; CHECK-NEXT:    xorl %ebx, %ebx
-; CHECK-NEXT:    jmp LBB0_16
-; CHECK-NEXT:  LBB0_10: ## %bb17
+; CHECK-NEXT:    jne LBB0_12
+; CHECK-NEXT:    jmp LBB0_14
+; CHECK-NEXT:  LBB0_8: ## %bb17
 ; CHECK-NEXT:    callq _PyErr_Occurred
 ; CHECK-NEXT:    testq %rax, %rax
-; CHECK-NEXT:    jne LBB0_23
-; CHECK-NEXT:  ## %bb.11: ## %cond_next
+; CHECK-NEXT:    jne LBB0_27
+; CHECK-NEXT:  ## %bb.9: ## %cond_next
 ; CHECK-NEXT:    movq _PyArray_API@GOTPCREL(%rip), %rax
 ; CHECK-NEXT:    movq (%rax), %rax
 ; CHECK-NEXT:    movq 80(%rax), %rax
-; CHECK-NEXT:  LBB0_9: ## %bb4
+; CHECK-NEXT:  LBB0_10: ## %bb4
 ; CHECK-NEXT:    movq 96(%rax), %rax
 ; CHECK-NEXT:    movq %r14, %rdi
 ; CHECK-NEXT:    movq %rbx, %rsi
 ; CHECK-NEXT:    callq *40(%rax)
-; CHECK-NEXT:    jmp LBB0_24
-; CHECK-NEXT:  LBB0_4: ## %cond_true.i
+; CHECK-NEXT:    jmp LBB0_28
+; CHECK-NEXT:  LBB0_11: ## %cond_true.i
 ; CHECK-NEXT:    movl $4, %edi
 ; CHECK-NEXT:    callq _feraiseexcept
 ; CHECK-NEXT:    movzbl {{[0-9]+}}(%rsp), %edx
 ; CHECK-NEXT:    movzbl {{[0-9]+}}(%rsp), %esi
+; CHECK-NEXT:    xorl %r15d, %r15d
 ; CHECK-NEXT:    testb %sil, %sil
-; CHECK-NEXT:    sete %al
+; CHECK-NEXT:    je LBB0_14
+; CHECK-NEXT:  LBB0_12: ## %cond_false.i
 ; CHECK-NEXT:    testb %dl, %dl
-; CHECK-NEXT:    sete %cl
-; CHECK-NEXT:    xorl %r15d, %r15d
-; CHECK-NEXT:    orb %al, %cl
-; CHECK-NEXT:    jne LBB0_13
-; CHECK-NEXT:  LBB0_5: ## %cond_next17.i
+; CHECK-NEXT:    je LBB0_14
+; CHECK-NEXT:  ## %bb.13: ## %cond_next17.i
 ; CHECK-NEXT:    movzbl %sil, %eax
 ; CHECK-NEXT:    divb %dl
 ; CHECK-NEXT:    movzbl %ah, %ebx
-; CHECK-NEXT:  LBB0_16: ## %ubyte_ctype_remainder.exit
+; CHECK-NEXT:    jmp LBB0_18
+; CHECK-NEXT:  LBB0_14: ## %cond_true.i200
+; CHECK-NEXT:    testb %dl, %dl
+; CHECK-NEXT:    jne LBB0_17
+; CHECK-NEXT:  ## %bb.16: ## %cond_true14.i
+; CHECK-NEXT:    movl $4, %edi
+; CHECK-NEXT:    callq _feraiseexcept
+; CHECK-NEXT:  LBB0_17: ## %ubyte_ctype_remainder.exit
+; CHECK-NEXT:    xorl %ebx, %ebx
+; CHECK-NEXT:  LBB0_18: ## %ubyte_ctype_remainder.exit
 ; CHECK-NEXT:    movq (%r14), %rax
 ; CHECK-NEXT:    callq *224(%rax)
 ; CHECK-NEXT:    testl %eax, %eax
-; CHECK-NEXT:    je LBB0_19
-; CHECK-NEXT:  ## %bb.17: ## %cond_true61
+; CHECK-NEXT:    je LBB0_21
+; CHECK-NEXT:  ## %bb.19: ## %cond_true61
 ; CHECK-NEXT:    movl %eax, %ebp
 ; CHECK-NEXT:    movq (%r14), %rax
 ; CHECK-NEXT:    movq _.str5@GOTPCREL(%rip), %rdi
@@ -139,8 +136,8 @@ define ptr @ubyte_divmod(ptr %a, ptr %b) {
 ; CHECK-NEXT:    leaq {{[0-9]+}}(%rsp), %rcx
 ; CHECK-NEXT:    callq *200(%rax)
 ; CHECK-NEXT:    testl %eax, %eax
-; CHECK-NEXT:    js LBB0_23
-; CHECK-NEXT:  ## %bb.18: ## %cond_next73
+; CHECK-NEXT:    js LBB0_27
+; CHECK-NEXT:  ## %bb.20: ## %cond_next73
 ; CHECK-NEXT:    movl $1, {{[0-9]+}}(%rsp)
 ; CHECK-NEXT:    movq (%r14), %rax
 ; CHECK-NEXT:    movq {{[0-9]+}}(%rsp), %rsi
@@ -149,13 +146,13 @@ define ptr @ubyte_divmod(ptr %a, ptr %b) {
 ; CHECK-NEXT:    movl %ebp, %edx
 ; CHECK-NEXT:    callq *232(%rax)
 ; CHECK-NEXT:    testl %eax, %eax
-; CHECK-NEXT:    jne LBB0_23
-; CHECK-NEXT:  LBB0_19: ## %cond_next89
+; CHECK-NEXT:    jne LBB0_27
+; CHECK-NEXT:  LBB0_21: ## %cond_next89
 ; CHECK-NEXT:    movl $2, %edi
 ; CHECK-NEXT:    callq _PyTuple_New
 ; CHECK-NEXT:    testq %rax, %rax
-; CHECK-NEXT:    je LBB0_23
-; CHECK-NEXT:  ## %bb.20: ## %cond_next97
+; CHECK-NEXT:    je LBB0_27
+; CHECK-NEXT:  ## %bb.22: ## %cond_next97
 ; CHECK-NEXT:    movq %rax, %r14
 ; CHECK-NEXT:    movq _PyArray_API@GOTPCREL(%rip), %r12
 ; CHECK-NEXT:    movq (%r12), %rax
@@ -163,8 +160,8 @@ define ptr @ubyte_divmod(ptr %a, ptr %b) {
 ; CHECK-NEXT:    xorl %esi, %esi
 ; CHECK-NEXT:    callq *304(%rdi)
 ; CHECK-NEXT:    testq %rax, %rax
-; CHECK-NEXT:    je LBB0_21
-; CHECK-NEXT:  ## %bb.25: ## %cond_next135
+; CHECK-NEXT:    je LBB0_25
+; CHECK-NEXT:  ## %bb.23: ## %cond_next135
 ; CHECK-NEXT:    movb %r15b, 16(%rax)
 ; CHECK-NEXT:    movq %rax, 24(%r14)
 ; CHECK-NEXT:    movq (%r12), %rax
@@ -172,22 +169,22 @@ define ptr @ubyte_divmod(ptr %a, ptr %b) {
 ; CHECK-NEXT:    xorl %esi, %esi
 ; CHECK-NEXT:    callq *304(%rdi)
 ; CHECK-NEXT:    testq %rax, %rax
-; CHECK-NEXT:    je LBB0_21
-; CHECK-NEXT:  ## %bb.26: ## %cond_next182
+; CHECK-NEXT:    je LBB0_25
+; CHECK-NEXT:  ## %bb.24: ## %cond_next182
 ; CHECK-NEXT:    movb %bl, 16(%rax)
 ; CHECK-NEXT:    movq %rax, 32(%r14)
 ; CHECK-NEXT:    movq %r14, %rax
-; CHECK-NEXT:    jmp LBB0_24
-; CHECK-NEXT:  LBB0_21: ## %cond_true113
+; CHECK-NEXT:    jmp LBB0_28
+; CHECK-NEXT:  LBB0_25: ## %cond_true113
 ; CHECK-NEXT:    decq (%r14)
-; CHECK-NEXT:    jne LBB0_23
-; CHECK-NEXT:  ## %bb.22: ## %cond_true126
+; CHECK-NEXT:    jne LBB0_27
+; CHECK-NEXT:  ## %bb.26: ## %cond_true126
 ; CHECK-NEXT:    movq 8(%r14), %rax
 ; CHECK-NEXT:    movq %r14, %rdi
 ; CHECK-NEXT:    callq *48(%rax)
-; CHECK-NEXT:  LBB0_23: ## %UnifiedReturnBlock
+; CHECK-NEXT:  LBB0_27: ## %UnifiedReturnBlock
 ; CHECK-NEXT:    xorl %eax, %eax
-; CHECK-NEXT:  LBB0_24: ## %UnifiedReturnBlock
+; CHECK-NEXT:  LBB0_28: ## %UnifiedReturnBlock
 ; CHECK-NEXT:    addq $32, %rsp
 ; CHECK-NEXT:    popq %rbx
 ; CHECK-NEXT:    popq %r12
diff --git a/llvm/test/CodeGen/X86/issue-160612.c b/llvm/test/CodeGen/X86/issue-160612.c
new file mode 100644
index 0000000000000..c7b231cc81b6c
--- /dev/null
+++ b/llvm/test/CodeGen/X86/issue-160612.c
@@ -0,0 +1,19 @@
+extern void subroutine_foo(void);
+extern void subroutine_bar(void);
+
+void func_a(int x, int y) {
+    if (x == 0 || y == 0)
+        subroutine_foo();
+    else
+        subroutine_bar();
+}
+
+void func_b(int x, int y) {
+    if (x == 0)
+        subroutine_foo();
+    else if (y == 0)
+        subroutine_foo();
+    else
+        subroutine_bar();
+}
+
diff --git a/llvm/test/CodeGen/X86/issue-160612.ll b/llvm/test/CodeGen/X86/issue-160612.ll
new file mode 100644
index 0000000000000..6572c421b7fe6
--- /dev/null
+++ b/llvm/test/CodeGen/X86/issue-160612.ll
@@ -0,0 +1,74 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu -O2 | FileCheck %s
+
+; Test for issue #160612: OR conditions in branches should use multiple branches
+; instead of materializing booleans with SETCC when no special optimizations apply.
+
+declare void @subroutine_foo()
+declare void @subroutine_bar()
+
+; Original issue: (x == 0 || y == 0) was generating SETCC + TEST + BRANCH
+; instead of using two conditional branches directly.
+define void @func_a(i32 noundef %x, i32 noundef %y) {
+; CHECK-LABEL: func_a:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    testl %edi, %edi
+; CHECK-NEXT:    je subroutine_foo@PLT # TAILCALL
+; CHECK-NEXT:  # %bb.1: # %entry
+; CHECK-NEXT:    testl %esi, %esi
+; CHECK-NEXT:    jne subroutine_bar@PLT # TAILCALL
+; CHECK-NEXT:  # %bb.2: # %if.then
+; CHECK-NEXT:    jmp subroutine_foo@PLT # TAILCALL
+entry:
+  %cmp = icmp eq i32 %x, 0
+  %cmp1 = icmp eq i32 %y, 0
+  %or.cond = or i1 %cmp, %cmp1
+  br i1 %or.cond, label %if.then, label %if.else
+
+if.then:
+  tail call void @subroutine_foo()
+  br label %if.end
+
+if.else:
+  tail call void @subroutine_bar()
+  br label %if.end
+
+if.end:
+  ret void
+}
+
+; Reference implementation that already generated optimal code.
+; This should continue to generate the same optimal code.
+define void @func_b(i32 noundef %x, i32 noundef %y) {
+; CHECK-LABEL: func_b:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    testl %edi, %edi
+; CHECK-NEXT:    je subroutine_foo@PLT # TAILCALL
+; CHECK-NEXT:  # %bb.1: # %if.else
+; CHECK-NEXT:    testl %esi, %esi
+; CHECK-NEXT:    je subroutine_foo@PLT # TAILCALL
+; CHECK-NEXT:  # %bb.2: # %if.else3
+; CHECK-NEXT:    jmp subroutine_bar@PLT # TAILCALL
+entry:
+  %cmp = icmp eq i32 %x, 0
+  br i1 %cmp, label %if.then, label %if.else
+
+if.then:
+  tail call void @subroutine_foo()
+  br label %if.end4
+
+if.else:
+  %cmp1 = icmp eq i32 %y, 0
+  br i1 %cmp1, label %if.then2, label %if.else3
+
+if.then2:
+  tail call void @subroutine_foo()
+  br label %if.end4
+
+if.else3:
+  tail call void @subroutine_bar()
+  br label %if.end4
+
+if.end4:
+  ret void
+}
diff --git a/llvm/test/CodeGen/X86/x86-shrink-wrap-unwind.ll b/llvm/test/CodeGen/X86/x86-shrink-wrap-unwind.ll
index 3349d31cad4b9..02d4d88a21682 100644
--- a/llvm/test/CodeGen/X86/x86-shrink-wrap-unwind.ll
+++ b/llvm/test/CodeGen/X86/x86-shrink-wrap-unwind.ll
@@ -181,40 +181,38 @@ define zeroext i1 @segmentedStack(ptr readonly %vk1, ptr readonly %vk2, i64 %key
 ; CHECK-LABEL: segmentedStack:
 ; CHECK:       ## %bb.0:
 ; CHECK-NEXT:    cmpq %gs:816, %rsp
-; CHECK-NEXT:    jbe LBB3_6
+; CHECK-NEXT:    jbe LBB3_7
 ; CHECK-NEXT:  LBB3_1: ## %entry
 ; CHECK-NEXT:    pushq %rax
 ; CHECK-NEXT:    .cfi_def_cfa_offset 16
-; CHECK-NEXT:    testq %rdi, %rdi
-; CHECK-NEXT:    sete %al
-; CHECK-NEXT:    testq %rsi, %rsi
-; CHECK-NEXT:    sete %cl
-; CHECK-NEXT:    orb %al, %cl
 ; CHECK-NEXT:    movq %rdi, %rax
 ; CHECK-NEXT:    orq %rsi, %rax
 ; CHECK-NEXT:    sete %al
-; CHECK-NEXT:    testb %cl, %cl
-; CHECK-NEXT:    jne LBB3_4
-; CHECK-NEXT:  ## %bb.2: ## %if.end4.i
+; CHECK-NEXT:    testq %rdi, %rdi
+; CHECK-NEXT:    je LBB3_5
+; CHECK-NEXT:  ## %bb.2: ## %entry
+; CHECK-NEXT:    testq %rsi, %rsi
+; CHECK-NEXT:    je LBB3_5
+; CHECK-NEXT:  ## %bb.3: ## %if.end4.i
 ; CHECK-NEXT:    movq 8(%rdi), %rdx
 ; CHECK-NEXT:    cmpq 8(%rsi), %rdx
-; CHECK-NEXT:    jne LBB3_5
-; CHECK-NEXT:  ## %bb.3: ## %land.rhs.i.i
+; CHECK-NEXT:    jne LBB3_6
+; CHECK-NEXT:  ## %bb.4: ## %land.rhs.i.i
 ; CHECK-NEXT:    movq (%rsi), %rsi
 ; CHECK-NEXT:    movq (%rdi), %rdi
 ; CHECK-NEXT:    callq _memcmp
 ; CHECK-NEXT:    testl %eax, %eax
 ; CHECK-NEXT:    sete %al
-; CHECK-NEXT:  LBB3_4: ## %__go_ptr_strings_equal.exit
+; CHECK-NEXT:  LBB3_5: ## %__go_ptr_strings_equal.exit
 ; CHECK-NEXT:    ## kill: def $al killed $al killed $eax
 ; CHECK-NEXT:    popq %rcx
 ; CHECK-NEXT:    retq
-; CHECK-NEXT:  LBB3_5:
+; CHECK-NEXT:  LBB3_6:
 ; CHECK-NEXT:    xorl %eax, %eax
 ; CHECK-NEXT:    ## kill: def $al killed $al killed $eax
 ; CHECK-NEXT:    popq %rcx
 ; CHECK-NEXT:    retq
-; CHECK-NEXT:  LBB3_6:
+; CHECK-NEXT:  LBB3_7:
 ; CHECK-NEXT:    movl $8, %r10d
 ; CHECK-NEXT:    movl $0, %r11d
 ; CHECK-NEXT:    callq ___morestack
@@ -224,43 +222,41 @@ define zeroext i1 @segmentedStack(ptr readonly %vk1, ptr readonly %vk2, i64 %key
 ; NOCOMPACTUNWIND-LABEL: segmentedStack:
 ; NOCOMPACTUNWIND:       # %bb.0:
 ; NOCOMPACTUNWIND-NEXT:    cmpq %fs:112, %rsp
-; NOCOMPACTUNWIND-NEXT:    jbe .LBB3_6
+; NOCOMPACTUNWIND-NEXT:    jbe .LBB3_7
 ; NOCOMPACTUNWIND-NEXT:  .LBB3_1: # %entry
 ; NOCOMPACTUNWIND-NEXT:    pushq %rax
 ; NOCOMPACTUNWIND-NEXT:    .cfi_def_cfa_offset 16
-; NOCOMPACTUNWIND-NEXT:    testq %rdi, %rdi
-; NOCOMPACTUNWIND-NEXT:    sete %al
-; NOCOMPACTUNWIND-NEXT:    testq %rsi, %rsi
-; NOCOMPACTUNWIND-NEXT:    sete %cl
-; NOCOMPACTUNWIND-NEXT:    orb %al, %cl
 ; NOCOMPACTUNWIND-NEXT:    movq %rdi, %rax
 ; NOCOMPACTUNWIND-NEXT:    orq %rsi, %rax
 ; NOCOMPACTUNWIND-NEXT:    sete %al
-; NOCOMPACTUNWIND-NEXT:    testb %cl, %cl
-; NOCOMPACTUNWIND-NEXT:    jne .LBB3_4
-; NOCOMPACTUNWIND-NEXT:  # %bb.2: # %if.end4.i
+; NOCOMPACTUNWIND-NEXT:    testq %rdi, %rdi
+; NOCOMPACTUNWIND-NEXT:    je .LBB3_5
+; NOCOMPACTUNWIND-NEXT:  # %bb.2: # %entry
+; NOCOMPACTUNWIND-NEXT:    testq %rsi, %rsi
+; NOCOMPACTUNWIND-NEXT:    je .LBB3_5
+; NOCOMPACTUNWIND-NEXT:  # %bb.3: # %if.end4.i
 ; NOCOMPACTUNWIND-NEXT:    movq 8(%rdi), %rdx
 ; NOCOMPACTUNWIND-NEXT:    cmpq 8(%rsi), %rdx
-; NOCOMPACTUNWIND-NEXT:    jne .LBB3_5
-; NOCOMPACTUNWIND-NEXT:  # %bb.3: # %land.rhs.i.i
+; NOCOMPACTUNWIND-NEXT:    jne .LBB3_6
+; NOCOMPACTUNWIND-NEXT:  # %bb.4: # %land.rhs.i.i
 ; NOCOMPACTUNWIND-NEXT:    movq (%rsi), %rsi
 ; NOCOMPACTUNWIND-NEXT:    movq (%rdi), %rdi
 ; NOCOMPACTUNWIND-NEXT:    callq memcmp@PLT
 ; NOCOMPACTUNWIND-NEXT:    testl %eax, %eax
 ; NOCOMPACTUNWIND-NEXT:    sete %al
-; NOCOMPACTUNWIND-NEXT:  .LBB3_4: # %__go_ptr_strings_equal.exit
+; NOCOMPACTUNWIND-NEXT:  .LBB3_5: # %__go_ptr_strings_equal.exit
 ; NOCOMPACTUNWIND-NEXT:    # kill: def $al killed $al killed $eax
 ; NOCOMPACTUNWIND-NEXT:    popq %rcx
 ; NOCOMPACTUNWIND-NEXT:    .cfi_def_cfa_offset 8
 ; NOCOMPACTUNWIND-NEXT:    retq
-; NOCOMPACTUNWIND-NEXT:  .LBB3_5:
+; NOCOMPACTUNWIND-NEXT:  .LBB3_6:
 ; NOCOMPACTUNWIND-NEXT:    .cfi_def_cfa_offset 16
 ; NOCOMPACTUNWIND-NEXT:    xorl %eax, %eax
 ; NOCOMPACTUNWIND-NEXT:    # kill: def $al killed $al killed $eax
 ; NOCOMPACTUNWIND-NEXT:    popq %rcx
 ; NOCOMPACTUNWIND-NEXT:    .cfi_def_cfa_offset 8
 ; NOCOMPACTUNWIND-NEXT:    retq
-; NOCOMPACTUNWIND-NEXT:  .LBB3_6:
+; NOCOMPACTUNWIND-NEXT:  .LBB3_7:
 ; NOCOMPACTUNWIND-NEXT:    movl $8, %r10d
 ; NOCOMPACTUNWIND-NEXT:    movl $0, %r11d
 ; NOCOMPACTUNWIND-NEXT:    callq __morestack
@@ -317,13 +313,13 @@ define void @with_nounwind(i1 %cond) nounwind personality ptr @my_personality {
 ; CHECK-NEXT:    popq %rax
 ; CHECK-NEXT:    retq
 ; CHECK-NEXT:  LBB4_1: ## %throw
-; CHECK-NEXT:  Ltmp0:
+; CHECK-NEXT:  Ltmp0: ## EH_LABEL
 ; CHECK-NEXT:    callq _throw_exception
-; CHECK-NEXT:  Ltmp1:
+; CHECK-NEXT:  Ltmp1: ## EH_LABEL
 ; CHECK-NEXT:  ## %bb.2: ## %unreachable
 ; CHECK-NEXT:    ud2
 ; CHECK-NEXT:  LBB4_3: ## %landing
-; CHECK-NEXT:  Ltmp2:
+; CHECK-NEXT:  Ltmp2: ## EH_LABEL
 ; CHECK-NEXT:    popq %rax
 ; CHECK-NEXT:    retq
 ; CHECK-NEXT:  Lfunc_end0:
@@ -340,12 +336,12 @@ define void @with_nounwind(i1 %cond) nounwind personality ptr @my_personality {
 ; NOCOMPACTUNWIND-NEXT:    retq
 ; NOCOMPACTUNWIND-NEXT:  .LBB4_1: # %throw
 ; NOCOMPACTUNWIND-NEXT:    .cfi_def_cfa_offset 16
-; NOCOMPACTUNWIND-NEXT:  .Ltmp0:
+; NOCOMPACTUNWIND-NEXT:  .Ltmp0: # EH_LABEL
 ; NOCOMPACTUNWIND-NEXT:    callq throw_exception@PLT
-; NOCOMPACTUNWIND-NEXT:  .Ltmp1:
+; NOCOMPACTUNWIND-NEXT:  .Ltmp1: # EH_LABEL
 ; NOCOMPACTUNWIND-NEXT:  # %bb.2: # %unreachable
 ; NOCOMPACTUNWIND-NEXT:  .LBB4_3: # %landing
-; NOCOMPACTUNWIND-NEXT:  .Ltmp2:
+; NOCOMPACTUNWIND-NEXT:  .Ltmp2: # EH_LABEL
 ; NOCOMPACTUNWIND-NEXT:    popq %rax
 ; NOCOMPACTUNWIND-NEXT:    .cfi_def_cfa_offset 8
 ; NOCOMPACTUNWIND-NEXT:    retq
@@ -379,9 +375,9 @@ define void @with_nounwind_same_succ(i1 %cond) nounwind personality ptr @my_pers
 ; CHECK-NEXT:  ## %bb.1: ## %throw
 ; CHECK-NEXT:    pushq %rax
 ; CHECK-NEXT:    .cfi_def_cfa_offset 16
-; CHECK-NEXT:  Ltmp3:
+; CHECK-NEXT:  Ltmp3: ## EH_LABEL
 ; CHECK-NEXT:    callq _throw_exception
-; CHECK-NEXT:  Ltmp4:
+; CHECK-NEXT:  Ltmp4: ## EH_LABEL
 ; CHECK-NEXT:  LBB5_3: ## %fallthrough
 ; CHECK-NEXT:    ## InlineAsm Start
 ; CHECK-NEXT:    nop
@@ -390,7 +386,7 @@ define void @with_nounwind_same_succ(i1 %cond) nounwind personality ptr @my_pers
 ; CHECK-NEXT:  LBB5_4: ## %return
 ; CHECK-NEXT:    retq
 ; CHECK-NEXT:  LBB5_2: ## %landing
-; CHECK-NEXT:  Ltmp5:
+; CHECK-NEXT:  Ltmp5: ## EH_LABEL
 ; CHECK-NEXT:    jmp LBB5_3
 ; CHECK-NEXT:  Lfunc_end1:
 ;
@@ -401,9 +397,9 @@ define void @with_nounwind_same_succ(i1 %cond) nounwind personality ptr @my_pers
 ; NOCOMPACTUNWIND-NEXT:  # %bb.1: # %throw
 ; NOCOMPACTUNWIND-NEXT:    pushq %rax
 ; NOCOMPACTUNWIND-NEXT:    .cfi_def_cfa_offset 16
-; NOCOMPACTUNWIND-NEXT:  .Ltmp3:
+; NOCOMPACTUNWIND-NEXT:  .Ltmp3: # EH_LABEL
 ; NOCOMPACTUNWIND-NEXT:    callq throw_exception@PLT
-; NOCOMPACTUNWIND-NEXT:  .Ltmp4:
+; NOCOMPACTUNWIND-NEXT:  .Ltmp4: # EH_LABEL
 ; NOCOMPACTUNWIND-NEXT:  .LBB5_3: # %fallthrough
 ; NOCOMPACTUNWIND-NEXT:    #APP
 ; NOCOMPACTUNWIND-NEXT:    nop
@@ -414,7 +410,7 @@ define void @with_nounwind_same_succ(i1 %cond) nounwind personality ptr @my_pers
 ; NOCOMPACTUNWIND-NEXT:    retq
 ; NOCOMPACTUNWIND-NEXT:  .LBB5_2: # %landing
 ; NOCOMPACTUNWIND-NEXT:    .cfi_def_cfa_offset 16
-; NOCOMPACTUNWIND-NEXT:  .Ltmp5:
+; NOCOMPACTUNWIND-NEXT:  .Ltmp5: # EH_LABEL
 ; NOCOMPACTUNWIND-NEXT:    jmp .LBB5_3
 entry:
   br i1 %cond, label %throw, label %return

github-actions · 2025-10-06T06:34:38Z

✅ With the latest revision this PR passed the C/C++ code formatter.

abhishek-kaushik22 · 2025-10-06T06:37:28Z

llvm/test/CodeGen/X86/issue-160612.c

@@ -0,0 +1,19 @@
+extern void subroutine_foo(void);


This should be deleted?

if you want to include these as references - best add them as comments above their respective IR implementation in the ll file

done -- deleted

abhishek-kaushik22 · 2025-10-06T07:07:59Z

llvm/lib/Target/X86/X86ISelLowering.cpp

+  // (unless CCMP is available). OR+EQ cannot be optimized via bitwise ops,
+  // unlike OR+NE which becomes (P|Q)!=0. Similarly, don't split signed
+  // comparisons (SLT, SGT) that can be optimized.
+  if (BaseCost >= 0 && !Subtarget.hasCCMP() && Opc == Instruction::Or) {


Can we use a match here like the previous check?

if (BaseCost >= 0 && !Subtarget.hasCCMP() && Opc == Instruction::Or && match(Lhs, m_SpecificICmp(ICmpInst::ICMP_EQ, m_Value(), m_Value())) && match(Rhs, m_SpecificICmp(ICmpInst::ICMP_EQ, m_Value(), m_Value()))) return {-1,-1,-1};

RKSimon

please merge against trunk and fix the CI failures

RKSimon · 2025-10-07T08:05:40Z

llvm/test/CodeGen/X86/issue-160612.c

@@ -0,0 +1,19 @@
+extern void subroutine_foo(void);


if you want to include these as references - best add them as comments above their respective IR implementation in the ll file

RKSimon · 2025-10-07T08:06:24Z

llvm/test/CodeGen/X86/issue-160612.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu -O2 | FileCheck %s
+
+; Test for issue #160612: OR conditions in branches should use multiple branches


(style) rename issue-160612.ll -> pr160612.ll (pr stands for problem report not pull request)

abhishek-kaushik22

LGTM, but please fix the formatting error.

abhishek-kaushik22

You should only format the lines you've changed, please don't format the entire file.

RKSimon

LGTM

github-actions · 2025-10-14T13:36:24Z

@manik-muk Congratulations on having your first Pull Request (PR) merged into the LLVM Project!

Your changes will be combined with recent changes from other authors, then tested by our build bots. If there is a problem with a build, you may receive a report in an email or a comment on this PR.

Please check whether problems have been caused by your change specifically, as the builds can include changes from many authors. It is not uncommon for your change to be included in a build that fails due to someone else's changes, or infrastructure issues.

How to do this, and the rest of the post-merge process, is covered in detail here.

If your change does cause a problem, it may be reverted, or you can revert it yourself. This is a normal part of LLVM development. You can fix your changes and open a new PR to merge them again.

If you don't get any reports, no action is required from you. Your changes are working as expected, well done!

…ch instructions (llvm#162041) Addresses llvm#160612

added optimization

1f963ab

llvmbot added the backend:X86 label Oct 6, 2025

abhishek-kaushik22 linked an issue Oct 6, 2025 that may be closed by this pull request

x86 optimization: logical AND and OR in if-conditionals can turn to multiple branch instructions #160612

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abhishek-kaushik22 requested changes Oct 6, 2025

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RKSimon self-requested a review October 6, 2025 07:41

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manik-muk and others added 3 commits October 9, 2025 23:22

addressed pr commments

6c1c962

Merge branch 'main' into reduceBranches

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Merge branch 'main' into reduceBranches

0443575

manik-muk requested review from RKSimon and abhishek-kaushik22 October 10, 2025 03:28

abhishek-kaushik22 approved these changes Oct 10, 2025

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abhishek-kaushik22 requested changes Oct 10, 2025

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reverted clang formatting to just my changes

bdaceab

manik-muk force-pushed the reduceBranches branch from 602ae39 to bdaceab Compare October 10, 2025 06:43

abhishek-kaushik22 approved these changes Oct 10, 2025

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Merge branch 'main' into reduceBranches

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RKSimon changed the title ~~logical AND and OR in if-conditionals can turn to multiple branch instructions~~ [X86] logical AND and OR in if-conditionals can turn to multiple branch instructions Oct 14, 2025

RKSimon approved these changes Oct 14, 2025

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Merge branch 'main' into reduceBranches

1841f70

RKSimon enabled auto-merge (squash) October 14, 2025 13:06

RKSimon merged commit 45495b5 into llvm:main Oct 14, 2025
9 of 10 checks passed

akadutta pushed a commit to akadutta/llvm-project that referenced this pull request Oct 14, 2025

[X86] logical AND and OR in if-conditionals can turn to multiple bran…

6c12d87

…ch instructions (llvm#162041) Addresses llvm#160612

[X86] logical AND and OR in if-conditionals can turn to multiple branch instructions #162041

[X86] logical AND and OR in if-conditionals can turn to multiple branch instructions #162041

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