[ValueTracking] Adjust known bits from select's condition

Author: dtcxzyw

llvm/lib/Analysis/ValueTracking.cpp

@@ -1574,11 +1574,13 @@ static void computeKnownBitsFromOperator(const Operator *I,
 
         // If the Use is a select of this phi, use the knownbit of the other
         // operand to break the recursion.
-        Value *V;
-        if (match(IncValue, m_Select(m_Value(), m_Specific(P), m_Value(V))) ||
-            match(IncValue, m_Select(m_Value(), m_Value(V), m_Specific(P)))) {
-          IncValue = V;
+        Value *IncCond = nullptr;
+        bool InvertIncCond = false;
+        if (auto *SI = dyn_cast<SelectInst>(IncValue)) {
+          InvertIncCond = SI->getTrueValue() == P;
+          IncValue = InvertIncCond ? SI->getFalseValue() : SI->getTrueValue();
           IncDepth = Depth + 1;
+          IncCond = SI->getCondition();
         }
 
         // Change the context instruction to the "edge" that flows into the
@@ -1590,6 +1592,9 @@ static void computeKnownBitsFromOperator(const Operator *I,
 
         Known2 = KnownBits(BitWidth);
         computeKnownBits(IncValue, DemandedElts, Known2, IncDepth, RecQ);
+        if (IncCond)
+          adjustKnownBitsForSelectArm(Known2, IncCond, IncValue, InvertIncCond,
+                                      Depth, RecQ);
 
         // See if we can further use a conditional branch into the phi
         // to help us determine the range of the value.

llvm/test/CodeGen/X86/2012-01-10-UndefExceptionEdge.ll

@@ -29,32 +29,29 @@ define void @f(ptr nocapture %arg, ptr nocapture %arg1, ptr nocapture %arg2, ptr
 ; CHECK-NEXT:    pushl %ebx
 ; CHECK-NEXT:    pushl %edi
 ; CHECK-NEXT:    pushl %esi
-; CHECK-NEXT:    subl $28, %esp
+; CHECK-NEXT:    subl $12, %esp
 ; CHECK-NEXT:    .cfi_offset %esi, -20
 ; CHECK-NEXT:    .cfi_offset %edi, -16
 ; CHECK-NEXT:    .cfi_offset %ebx, -12
 ; CHECK-NEXT:    xorl %eax, %eax
-; CHECK-NEXT:    xorl %edi, %edi
 ; CHECK-NEXT:    testb %al, %al
 ; CHECK-NEXT:  Ltmp0:
-; CHECK-NEXT:    ## implicit-def: $ebx
+; CHECK-NEXT:    ## implicit-def: $edi
 ; CHECK-NEXT:    calll __Znam
 ; CHECK-NEXT:  Ltmp1:
 ; CHECK-NEXT:  ## %bb.1: ## %bb11
 ; CHECK-NEXT:    movl %eax, %esi
-; CHECK-NEXT:    movb $1, %al
-; CHECK-NEXT:    testb %al, %al
+; CHECK-NEXT:    movb $1, %bl
+; CHECK-NEXT:    testb %bl, %bl
 ; CHECK-NEXT:    jne LBB0_2
 ; CHECK-NEXT:  ## %bb.7: ## %bb31
-; CHECK-NEXT:    ## implicit-def: $eax
-; CHECK-NEXT:    ## kill: killed $eax
+; CHECK-NEXT:    ## implicit-def: $edi
 ; CHECK-NEXT:  LBB0_8: ## %bb38
 ; CHECK-NEXT:    ## =>This Loop Header: Depth=1
 ; CHECK-NEXT:    ## Child Loop BB0_13 Depth 2
 ; CHECK-NEXT:    ## Child Loop BB0_16 Depth 3
 ; CHECK-NEXT:    ## Child Loop BB0_21 Depth 2
-; CHECK-NEXT:    movb $1, %al
-; CHECK-NEXT:    testb %al, %al
+; CHECK-NEXT:    testb %bl, %bl
 ; CHECK-NEXT:    jne LBB0_9
 ; CHECK-NEXT:  ## %bb.10: ## %bb41
 ; CHECK-NEXT:    ## in Loop: Header=BB0_8 Depth=1
@@ -78,8 +75,7 @@ define void @f(ptr nocapture %arg, ptr nocapture %arg1, ptr nocapture %arg2, ptr
 ; CHECK-NEXT:    ## Parent Loop BB0_8 Depth=1
 ; CHECK-NEXT:    ## => This Loop Header: Depth=2
 ; CHECK-NEXT:    ## Child Loop BB0_16 Depth 3
-; CHECK-NEXT:    movb $1, %cl
-; CHECK-NEXT:    testb %cl, %cl
+; CHECK-NEXT:    testb %bl, %bl
 ; CHECK-NEXT:    jne LBB0_19
 ; CHECK-NEXT:  ## %bb.14: ## %bb48
 ; CHECK-NEXT:    ## in Loop: Header=BB0_13 Depth=2
@@ -88,14 +84,13 @@ define void @f(ptr nocapture %arg, ptr nocapture %arg1, ptr nocapture %arg2, ptr
 ; CHECK-NEXT:    ## in Loop: Header=BB0_13 Depth=2
 ; CHECK-NEXT:    xorl %ecx, %ecx
 ; CHECK-NEXT:    movl %esi, %edx
-; CHECK-NEXT:    movl %edi, %ebx
 ; CHECK-NEXT:  LBB0_16: ## %bb49
 ; CHECK-NEXT:    ## Parent Loop BB0_8 Depth=1
 ; CHECK-NEXT:    ## Parent Loop BB0_13 Depth=2
 ; CHECK-NEXT:    ## => This Inner Loop Header: Depth=3
 ; CHECK-NEXT:    incl %ecx
 ; CHECK-NEXT:    addl $4, %edx
-; CHECK-NEXT:    decl %ebx
+; CHECK-NEXT:    testb %bl, %bl
 ; CHECK-NEXT:    jne LBB0_16
 ; CHECK-NEXT:  LBB0_17: ## %bb57
 ; CHECK-NEXT:    ## in Loop: Header=BB0_13 Depth=2
@@ -107,44 +102,42 @@ define void @f(ptr nocapture %arg, ptr nocapture %arg1, ptr nocapture %arg2, ptr
 ; CHECK-NEXT:    movl %eax, {{[0-9]+}}(%esp)
 ; CHECK-NEXT:    movl $0, (%esp)
 ; CHECK-NEXT:    calll ___bzero
-; CHECK-NEXT:    movb $1, %al
-; CHECK-NEXT:    testb %al, %al
+; CHECK-NEXT:    testb %bl, %bl
 ; CHECK-NEXT:    jne LBB0_22
 ; CHECK-NEXT:  ## %bb.20: ## %bb61.preheader
 ; CHECK-NEXT:    ## in Loop: Header=BB0_8 Depth=1
 ; CHECK-NEXT:    movl %esi, %eax
-; CHECK-NEXT:    movl %edi, %ecx
 ; CHECK-NEXT:  LBB0_21: ## %bb61
 ; CHECK-NEXT:    ## Parent Loop BB0_8 Depth=1
 ; CHECK-NEXT:    ## => This Inner Loop Header: Depth=2
 ; CHECK-NEXT:    movl $0, (%eax)
 ; CHECK-NEXT:    addl $4, %eax
-; CHECK-NEXT:    decl %ecx
+; CHECK-NEXT:    testb %bl, %bl
 ; CHECK-NEXT:    jne LBB0_21
 ; CHECK-NEXT:  LBB0_22: ## %bb67
 ; CHECK-NEXT:    ## in Loop: Header=BB0_8 Depth=1
-; CHECK-NEXT:    decl {{[-0-9]+}}(%e{{[sb]}}p) ## 4-byte Folded Spill
+; CHECK-NEXT:    decl %edi
 ; CHECK-NEXT:    jmp LBB0_8
 ; CHECK-NEXT:  LBB0_18: ## %bb43
 ; CHECK-NEXT:  Ltmp5:
-; CHECK-NEXT:    movl %esi, %ebx
+; CHECK-NEXT:    movl %esi, %edi
 ; CHECK-NEXT:    calll _OnOverFlow
 ; CHECK-NEXT:  Ltmp6:
 ; CHECK-NEXT:    jmp LBB0_3
 ; CHECK-NEXT:  LBB0_2: ## %bb29
 ; CHECK-NEXT:  Ltmp7:
-; CHECK-NEXT:    movl %esi, %ebx
+; CHECK-NEXT:    movl %esi, %edi
 ; CHECK-NEXT:    calll _OnOverFlow
 ; CHECK-NEXT:  Ltmp8:
 ; CHECK-NEXT:  LBB0_3: ## %bb30
 ; CHECK-NEXT:    ud2
 ; CHECK-NEXT:  LBB0_4: ## %bb20.loopexit
 ; CHECK-NEXT:  Ltmp4:
 ; CHECK-NEXT:  LBB0_9:
-; CHECK-NEXT:    movl %esi, %ebx
+; CHECK-NEXT:    movl %esi, %edi
 ; CHECK-NEXT:  LBB0_6: ## %bb23
-; CHECK-NEXT:    testl %ebx, %ebx
-; CHECK-NEXT:    addl $28, %esp
+; CHECK-NEXT:    testl %edi, %edi
+; CHECK-NEXT:    addl $12, %esp
 ; CHECK-NEXT:    popl %esi
 ; CHECK-NEXT:    popl %edi
 ; CHECK-NEXT:    popl %ebx

llvm/test/Transforms/InstCombine/cast-mul-select.ll

@@ -182,8 +182,6 @@ define void @PR36225(i32 %a, i32 %b, i1 %c1, i3 %v1, i3 %v2) {
 ; CHECK:       while.body:
 ; CHECK-NEXT:    br i1 [[C1:%.*]], label [[FOR_BODY3_US:%.*]], label [[FOR_BODY3:%.*]]
 ; CHECK:       for.body3.us:
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i32 [[B:%.*]], 0
-; CHECK-NEXT:    [[SPEC_SELECT:%.*]] = select i1 [[TOBOOL]], i8 0, i8 4
 ; CHECK-NEXT:    switch i3 [[V1:%.*]], label [[EXIT:%.*]] [
 ; CHECK-NEXT:      i3 0, label [[FOR_END:%.*]]
 ; CHECK-NEXT:      i3 -1, label [[FOR_END]]
@@ -194,9 +192,7 @@ define void @PR36225(i32 %a, i32 %b, i1 %c1, i3 %v1, i3 %v2) {
 ; CHECK-NEXT:      i3 -1, label [[FOR_END]]
 ; CHECK-NEXT:    ]
 ; CHECK:       for.end:
-; CHECK-NEXT:    [[H:%.*]] = phi i8 [ [[SPEC_SELECT]], [[FOR_BODY3_US]] ], [ [[SPEC_SELECT]], [[FOR_BODY3_US]] ], [ 0, [[FOR_BODY3]] ], [ 0, [[FOR_BODY3]] ]
-; CHECK-NEXT:    [[CONV:%.*]] = zext nneg i8 [[H]] to i32
-; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[A:%.*]], [[CONV]]
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[A:%.*]], 0
 ; CHECK-NEXT:    br i1 [[CMP]], label [[EXIT]], label [[EXIT2:%.*]]
 ; CHECK:       exit2:
 ; CHECK-NEXT:    unreachable
@@ -210,10 +206,8 @@ define void @PR36225(i32 %a, i32 %b, i1 %c1, i3 %v1, i3 %v2) {
 ; DBGINFO-NEXT:      #dbg_value(i32 [[B:%.*]], [[META89:![0-9]+]], !DIExpression(DW_OP_lit0, DW_OP_eq, DW_OP_stack_value), [[META95:![0-9]+]])
 ; DBGINFO-NEXT:    br i1 [[C1:%.*]], label [[FOR_BODY3_US:%.*]], label [[FOR_BODY3:%.*]], !dbg [[DBG96:![0-9]+]]
 ; DBGINFO:       for.body3.us:
-; DBGINFO-NEXT:    [[TOBOOL:%.*]] = icmp eq i32 [[B]], 0, !dbg [[META95]]
-; DBGINFO-NEXT:      #dbg_value(i1 [[TOBOOL]], [[META89]], !DIExpression(), [[META95]])
-; DBGINFO-NEXT:    [[SPEC_SELECT:%.*]] = select i1 [[TOBOOL]], i8 0, i8 4, !dbg [[DBG97:![0-9]+]]
-; DBGINFO-NEXT:      #dbg_value(i8 [[SPEC_SELECT]], [[META90:![0-9]+]], !DIExpression(), [[DBG97]])
+; DBGINFO-NEXT:      #dbg_value(i32 [[B]], [[META89]], !DIExpression(DW_OP_lit0, DW_OP_eq, DW_OP_stack_value), [[META95]])
+; DBGINFO-NEXT:      #dbg_value(i8 poison, [[META90:![0-9]+]], !DIExpression(), [[META97:![0-9]+]])
 ; DBGINFO-NEXT:    switch i3 [[V1:%.*]], label [[EXIT:%.*]] [
 ; DBGINFO-NEXT:      i3 0, label [[FOR_END:%.*]]
 ; DBGINFO-NEXT:      i3 -1, label [[FOR_END]]
@@ -224,11 +218,9 @@ define void @PR36225(i32 %a, i32 %b, i1 %c1, i3 %v1, i3 %v2) {
 ; DBGINFO-NEXT:      i3 -1, label [[FOR_END]]
 ; DBGINFO-NEXT:    ], !dbg [[DBG99:![0-9]+]]
 ; DBGINFO:       for.end:
-; DBGINFO-NEXT:    [[H:%.*]] = phi i8 [ [[SPEC_SELECT]], [[FOR_BODY3_US]] ], [ [[SPEC_SELECT]], [[FOR_BODY3_US]] ], [ 0, [[FOR_BODY3]] ], [ 0, [[FOR_BODY3]] ], !dbg [[DBG100:![0-9]+]]
-; DBGINFO-NEXT:      #dbg_value(i8 [[H]], [[META91:![0-9]+]], !DIExpression(), [[DBG100]])
-; DBGINFO-NEXT:    [[CONV:%.*]] = zext nneg i8 [[H]] to i32, !dbg [[DBG101:![0-9]+]]
-; DBGINFO-NEXT:      #dbg_value(i32 [[CONV]], [[META92:![0-9]+]], !DIExpression(), [[DBG101]])
-; DBGINFO-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[A:%.*]], [[CONV]], !dbg [[DBG102:![0-9]+]]
+; DBGINFO-NEXT:      #dbg_value(i8 poison, [[META91:![0-9]+]], !DIExpression(), [[META100:![0-9]+]])
+; DBGINFO-NEXT:      #dbg_value(i8 0, [[META92:![0-9]+]], !DIExpression(DW_OP_LLVM_convert, 8, DW_ATE_unsigned, DW_OP_LLVM_convert, 32, DW_ATE_unsigned, DW_OP_stack_value), [[META101:![0-9]+]])
+; DBGINFO-NEXT:    [[CMP:%.*]] = icmp sgt i32 [[A:%.*]], 0, !dbg [[DBG102:![0-9]+]]
 ; DBGINFO-NEXT:      #dbg_value(i1 [[CMP]], [[META93:![0-9]+]], !DIExpression(), [[DBG102]])
 ; DBGINFO-NEXT:    br i1 [[CMP]], label [[EXIT]], label [[EXIT2:%.*]], !dbg [[DBG103:![0-9]+]]
 ; DBGINFO:       exit2: