[profcheck] Propagate profile metadata in trunc(select) transform

[jinhuang1102]

In the AggressiveInstCombine pass, profile metadata was being dropped during the transformation of trunc(select(...)) operations. This change fixes the issue by propagating the metadata from the original select to the new trunc-select instruction.

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Jin Huang (jinhuang1102)

Changes

In the AggressiveInstCombine pass, profile metadata was being dropped during the transformation of trunc(select(...)) operations. This change fixes the issue by propagating the metadata from the original select to the new trunc-select instruction.

---

Full diff: https://github.com/llvm/llvm-project/pull/162406.diff

3 Files Affected:

• (modified) llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp (+1-1)
• (modified) llvm/test/Transforms/AggressiveInstCombine/trunc_select.ll (+6-2)
• (modified) llvm/test/Transforms/AggressiveInstCombine/trunc_select_cmp.ll (+6-2)

diff --git a/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp b/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp
index 9b9e2bac5db32..9150b58d0acf1 100644
--- a/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp
+++ b/llvm/lib/Transforms/AggressiveInstCombine/TruncInstCombine.cpp
@@ -459,7 +459,7 @@ void TruncInstCombine::ReduceExpressionGraph(Type *SclTy) {
       Value *Op0 = I->getOperand(0);
       Value *LHS = getReducedOperand(I->getOperand(1), SclTy);
       Value *RHS = getReducedOperand(I->getOperand(2), SclTy);
-      Res = Builder.CreateSelect(Op0, LHS, RHS);
+      Res = Builder.CreateSelect(Op0, LHS, RHS, "", I);
       break;
     }
     case Instruction::PHI: {
diff --git a/llvm/test/Transforms/AggressiveInstCombine/trunc_select.ll b/llvm/test/Transforms/AggressiveInstCombine/trunc_select.ll
index fb147821889db..f695416ce63d6 100644
--- a/llvm/test/Transforms/AggressiveInstCombine/trunc_select.ll
+++ b/llvm/test/Transforms/AggressiveInstCombine/trunc_select.ll
@@ -3,10 +3,11 @@
 
 target datalayout = "e-m:m-p1:64:64:64-p:32:32:32-n8:16:32"
 
-define dso_local i16 @select_i16(i16 %a, i16 %b, i1 %cond) {
+define dso_local i16 @select_i16(i16 %a, i16 %b, i1 %cond) !prof !0 {
 ; CHECK-LABEL: @select_i16(
+; CHECK: !prof [[PROF_0:![0-9]+]] {
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[COND:%.*]], i16 [[A:%.*]], i16 [[B:%.*]]
+; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[COND:%.*]], i16 [[A:%.*]], i16 [[B:%.*]], !prof [[PROF_1:![0-9]+]]
 ; CHECK-NEXT:    ret i16 [[SEL]]
 ;
 entry:
@@ -134,3 +135,6 @@ entry:
   ret i16 %conv4
 }
 
+!0 = !{!"function_entry_count", i64 1000}
+; CHECK: [[PROF_0]] = !{!"function_entry_count", i64 1000}
+; CHECK: [[PROF_1]] = !{!"branch_weights", i32 2, i32 3}
\ No newline at end of file
diff --git a/llvm/test/Transforms/AggressiveInstCombine/trunc_select_cmp.ll b/llvm/test/Transforms/AggressiveInstCombine/trunc_select_cmp.ll
index ac9cf2dbd89b8..5252fd93e4d97 100644
--- a/llvm/test/Transforms/AggressiveInstCombine/trunc_select_cmp.ll
+++ b/llvm/test/Transforms/AggressiveInstCombine/trunc_select_cmp.ll
@@ -1,12 +1,13 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -passes=aggressive-instcombine -S | FileCheck %s
 
-define dso_local i16 @cmp_select_sext_const(i8 %a) {
+define dso_local i16 @cmp_select_sext_const(i8 %a) !prof !0 {
 ; CHECK-LABEL: @cmp_select_sext_const(
+; CHECK: !prof [[PROF_0:![0-9]+]] {
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[CONV:%.*]] = sext i8 [[A:%.*]] to i32
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[CONV]], 109
-; CHECK-NEXT:    [[COND:%.*]] = select i1 [[CMP]], i32 109, i32 [[CONV]]
+; CHECK-NEXT:    [[COND:%.*]] = select i1 [[CMP]], i32 109, i32 [[CONV]], !prof [[PROF_1:![0-9]+]]
 ; CHECK-NEXT:    [[CONV4:%.*]] = trunc i32 [[COND]] to i16
 ; CHECK-NEXT:    ret i16 [[CONV4]]
 ;
@@ -209,3 +210,6 @@ define i16 @cmp_select_unsigned_const_i16Const_noTransformation(i8 %a) {
   ret i16 %conv4
 }
 
+!0 = !{!"function_entry_count", i64 1000}
+; CHECK: [[PROF_0]] = !{!"function_entry_count", i64 1000}
+; CHECK: [[PROF_1]] = !{!"branch_weights", i32 2, i32 3}