[InstCombine] Set !prof metadata on Selects identified by add.ll test

These select instructions are created from non-branching instructions,
so their branch weights are unknown.

Tracking issue: #147390

Author: alanzhao1

llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp

@@ -24,6 +24,7 @@
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/PatternMatch.h"
+#include "llvm/IR/ProfDataUtils.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Value.h"
 #include "llvm/Support/AlignOf.h"
@@ -878,13 +879,18 @@ Instruction *InstCombinerImpl::foldAddWithConstant(BinaryOperator &Add) {
     return BinaryOperator::CreateAdd(Builder.CreateNot(Y), X);
 
   // zext(bool) + C -> bool ? C + 1 : C
+  SelectInst *SI = nullptr;
   if (match(Op0, m_ZExt(m_Value(X))) &&
       X->getType()->getScalarSizeInBits() == 1)
-    return SelectInst::Create(X, InstCombiner::AddOne(Op1C), Op1);
+    SI = SelectInst::Create(X, InstCombiner::AddOne(Op1C), Op1);
   // sext(bool) + C -> bool ? C - 1 : C
   if (match(Op0, m_SExt(m_Value(X))) &&
       X->getType()->getScalarSizeInBits() == 1)
-    return SelectInst::Create(X, InstCombiner::SubOne(Op1C), Op1);
+    SI = SelectInst::Create(X, InstCombiner::SubOne(Op1C), Op1);
+  if (SI) {
+    setExplicitlyUnknownBranchWeights(*SI, DEBUG_TYPE);
+    return SI;
+  }
 
   // ~X + C --> (C-1) - X
   if (match(Op0, m_Not(m_Value(X)))) {

llvm/lib/Transforms/InstCombine/InstCombineShifts.cpp

@@ -14,6 +14,7 @@
 #include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/PatternMatch.h"
+#include "llvm/IR/ProfDataUtils.h"
 #include "llvm/Transforms/InstCombine/InstCombiner.h"
 using namespace llvm;
 using namespace PatternMatch;
@@ -1253,7 +1254,9 @@ Instruction *InstCombinerImpl::visitShl(BinaryOperator &I) {
     // shl (zext i1 X), C1 --> select (X, 1 << C1, 0)
     if (match(Op0, m_ZExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)) {
       auto *NewC = Builder.CreateShl(ConstantInt::get(Ty, 1), C1);
-      return SelectInst::Create(X, NewC, ConstantInt::getNullValue(Ty));
+      auto *SI = SelectInst::Create(X, NewC, ConstantInt::getNullValue(Ty));
+      setExplicitlyUnknownBranchWeights(*SI, DEBUG_TYPE);
+      return SI;
     }
   }
 

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

@@ -81,6 +81,7 @@
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/IR/PatternMatch.h"
+#include "llvm/IR/ProfDataUtils.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Use.h"
 #include "llvm/IR/User.h"
@@ -1735,7 +1736,9 @@ Instruction *InstCombinerImpl::foldBinopOfSextBoolToSelect(BinaryOperator &BO) {
   Constant *Zero = ConstantInt::getNullValue(BO.getType());
   Value *TVal = Builder.CreateBinOp(BO.getOpcode(), Ones, C);
   Value *FVal = Builder.CreateBinOp(BO.getOpcode(), Zero, C);
-  return SelectInst::Create(X, TVal, FVal);
+  SelectInst *SI = SelectInst::Create(X, TVal, FVal);
+  setExplicitlyUnknownBranchWeights(*SI, DEBUG_TYPE);
+  return SI;
 }
 
 static Value *simplifyOperationIntoSelectOperand(Instruction &I, SelectInst *SI,

llvm/test/Transforms/InstCombine/preserve-profile.ll

@@ -46,9 +46,48 @@ define i32 @NegBin(i1 %C) !prof !0 {
   ret i32 %V
 }
 
+define i32 @select_C_minus_1_or_C_from_bool(i1 %x) {
+; CHECK-LABEL: define i32 @select_C_minus_1_or_C_from_bool(
+; CHECK-SAME: i1 [[X:%.*]]) {
+; CHECK-NEXT:    [[ADD:%.*]] = select i1 [[X]], i32 41, i32 42, !prof [[PROF2:![0-9]+]]
+; CHECK-NEXT:    ret i32 [[ADD]]
+;
+  %ext = sext i1 %x to i32
+  %add = add i32 %ext, 42
+  ret i32 %add
+}
+
+define i5 @and_add(i1 %x, i1 %y) {
+; CHECK-LABEL: define i5 @and_add(
+; CHECK-SAME: i1 [[X:%.*]], i1 [[Y:%.*]]) {
+; CHECK-NEXT:    [[TMP1:%.*]] = xor i1 [[X]], true
+; CHECK-NEXT:    [[TMP2:%.*]] = and i1 [[Y]], [[TMP1]]
+; CHECK-NEXT:    [[R:%.*]] = select i1 [[TMP2]], i5 -2, i5 0, !prof [[PROF2]]
+; CHECK-NEXT:    ret i5 [[R]]
+;
+  %xz = zext i1 %x to i5
+  %ys = sext i1 %y to i5
+  %sub = add i5 %xz, %ys
+  %r = and i5 %sub, 30
+  ret i5 %r
+}
+
+define i32 @add_zext_zext_i1(i1 %a) {
+; CHECK-LABEL: define i32 @add_zext_zext_i1(
+; CHECK-SAME: i1 [[A:%.*]]) {
+; CHECK-NEXT:    [[ADD:%.*]] = select i1 [[A]], i32 2, i32 0, !prof [[PROF2]]
+; CHECK-NEXT:    ret i32 [[ADD]]
+;
+  %zext = zext i1 %a to i32
+  %add = add i32 %zext, %zext
+  ret i32 %add
+}
+
+
 !0 = !{!"function_entry_count", i64 1000}
 !1 = !{!"branch_weights", i32 2, i32 3}
 ;.
 ; CHECK: [[PROF0]] = !{!"function_entry_count", i64 1000}
 ; CHECK: [[PROF1]] = !{!"branch_weights", i32 2, i32 3}
+; CHECK: [[PROF2]] = !{!"unknown", !"instcombine"}
 ;.

llvm/utils/profcheck-xfail.txt

@@ -836,8 +836,6 @@ Transforms/InstCombine/2011-02-14-InfLoop.ll
 Transforms/InstCombine/AArch64/sve-intrinsic-sel.ll
 Transforms/InstCombine/AArch64/sve-intrinsic-simplify-binop.ll
 Transforms/InstCombine/AArch64/sve-intrinsic-simplify-shift.ll
-Transforms/InstCombine/add2.ll
-Transforms/InstCombine/add.ll
 Transforms/InstCombine/add-mask.ll
 Transforms/InstCombine/add-shl-mul-umax.ll
 Transforms/InstCombine/add-shl-sdiv-to-srem.ll