[llvm] 9a0f251 - [SelectOpt] Support ADD and SUB with zext operands. (#115489)

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Sat Nov 30 13:05:44 PST 2024


Author: Florian Hahn
Date: 2024-11-30T21:05:41Z
New Revision: 9a0f25158c2eff539de1efbd55de71e711135db7

URL: https://github.com/llvm/llvm-project/commit/9a0f25158c2eff539de1efbd55de71e711135db7
DIFF: https://github.com/llvm/llvm-project/commit/9a0f25158c2eff539de1efbd55de71e711135db7.diff

LOG: [SelectOpt] Support ADD and SUB with zext operands. (#115489)

Extend the support for implicit selects in the form of OR with a ZExt
operand to support ADD and SUB binops as well. They similarly can form
implicit selects which can be profitable to convert back the branches.

PR: https://github.com/llvm/llvm-project/pull/115489

Added: 
    

Modified: 
    llvm/lib/CodeGen/SelectOptimize.cpp
    llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
    llvm/test/CodeGen/AArch64/selectopt-cast.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/SelectOptimize.cpp b/llvm/lib/CodeGen/SelectOptimize.cpp
index d480642171e8e5..484705eabbc42e 100644
--- a/llvm/lib/CodeGen/SelectOptimize.cpp
+++ b/llvm/lib/CodeGen/SelectOptimize.cpp
@@ -489,8 +489,10 @@ static Value *getTrueOrFalseValue(
   }
 
   auto *BO = cast<BinaryOperator>(SI.getI());
-  assert(BO->getOpcode() == Instruction::Or &&
-         "Only currently handling Or instructions.");
+  assert((BO->getOpcode() == Instruction::Add ||
+          BO->getOpcode() == Instruction::Or ||
+          BO->getOpcode() == Instruction::Sub) &&
+         "Only currently handling Add, Or and Sub binary operators.");
 
   auto *CBO = BO->clone();
   auto CondIdx = SI.getConditionOpIndex();
@@ -786,8 +788,23 @@ void SelectOptimizeImpl::collectSelectGroups(BasicBlock &BB,
     // An Or(zext(i1 X), Y) can also be treated like a select, with condition X
     // and values Y|1 and Y.
     if (auto *BO = dyn_cast<BinaryOperator>(I)) {
-      if (BO->getType()->isIntegerTy(1) || BO->getOpcode() != Instruction::Or)
-        return SelectInfo.end();
+      switch (I->getOpcode()) {
+      case Instruction::Add:
+      case Instruction::Sub: {
+        Value *X;
+        if (!((PatternMatch::match(I->getOperand(0),
+                                   m_OneUse(m_ZExt(m_Value(X)))) ||
+               PatternMatch::match(I->getOperand(1),
+                                   m_OneUse(m_ZExt(m_Value(X))))) &&
+              X->getType()->isIntegerTy(1)))
+          return SelectInfo.end();
+        break;
+      }
+      case Instruction::Or:
+        if (BO->getType()->isIntegerTy(1) || BO->getOpcode() != Instruction::Or)
+          return SelectInfo.end();
+        break;
+      }
 
       for (unsigned Idx = 0; Idx < 2; Idx++) {
         auto *Op = BO->getOperand(Idx);

diff  --git a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
index 919226eb54fa59..5b333d33cffd52 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
@@ -4797,14 +4797,20 @@ AArch64TTIImpl::getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
 }
 
 bool AArch64TTIImpl::shouldTreatInstructionLikeSelect(const Instruction *I) {
-  // For the binary operators (e.g. or) we need to be more careful than
-  // selects, here we only transform them if they are already at a natural
-  // break point in the code - the end of a block with an unconditional
-  // terminator.
-  if (EnableOrLikeSelectOpt && I->getOpcode() == Instruction::Or &&
-      isa<BranchInst>(I->getNextNode()) &&
-      cast<BranchInst>(I->getNextNode())->isUnconditional())
-    return true;
+  if (EnableOrLikeSelectOpt) {
+    // For the binary operators (e.g. or) we need to be more careful than
+    // selects, here we only transform them if they are already at a natural
+    // break point in the code - the end of a block with an unconditional
+    // terminator.
+    if (I->getOpcode() == Instruction::Or &&
+        isa<BranchInst>(I->getNextNode()) &&
+        cast<BranchInst>(I->getNextNode())->isUnconditional())
+      return true;
+
+    if (I->getOpcode() == Instruction::Add ||
+        I->getOpcode() == Instruction::Sub)
+      return true;
+  }
   return BaseT::shouldTreatInstructionLikeSelect(I);
 }
 

diff  --git a/llvm/test/CodeGen/AArch64/selectopt-cast.ll b/llvm/test/CodeGen/AArch64/selectopt-cast.ll
index c15e6e1d1b697c..102b89df32b03b 100644
--- a/llvm/test/CodeGen/AArch64/selectopt-cast.ll
+++ b/llvm/test/CodeGen/AArch64/selectopt-cast.ll
@@ -7,16 +7,22 @@ define void @test_add_zext(ptr %dst, ptr %src, i64 %j.start, i64 %p, i64 %i.star
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
-; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
-; CHECK-NEXT:    [[J:%.*]] = phi i64 [ [[HIGH:%.*]], [[ENTRY]] ], [ [[J_NEXT:%.*]], [[LOOP]] ]
-; CHECK-NEXT:    [[I:%.*]] = phi i64 [ [[I_START:%.*]], [[ENTRY]] ], [ [[J_NEXT]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[SELECT_END:%.*]] ]
+; CHECK-NEXT:    [[J:%.*]] = phi i64 [ [[HIGH:%.*]], [[ENTRY]] ], [ [[J_NEXT:%.*]], [[SELECT_END]] ]
+; CHECK-NEXT:    [[I:%.*]] = phi i64 [ [[I_START:%.*]], [[ENTRY]] ], [ [[J_NEXT]], [[SELECT_END]] ]
 ; CHECK-NEXT:    [[GEP_I:%.*]] = getelementptr inbounds ptr, ptr [[SRC:%.*]], i64 [[I]]
 ; CHECK-NEXT:    [[L_I:%.*]] = load ptr, ptr [[GEP_I]], align 8
 ; CHECK-NEXT:    [[GEP_J:%.*]] = getelementptr inbounds ptr, ptr [[SRC]], i64 [[J]]
 ; CHECK-NEXT:    [[L_J:%.*]] = load ptr, ptr [[GEP_J]], align 8
 ; CHECK-NEXT:    [[CMP3:%.*]] = icmp ult ptr [[L_I]], [[L_J]]
 ; CHECK-NEXT:    [[DEC:%.*]] = zext i1 [[CMP3]] to i64
-; CHECK-NEXT:    [[J_NEXT]] = add nsw i64 [[J]], [[DEC]]
+; CHECK-NEXT:    [[CMP3_FROZEN:%.*]] = freeze i1 [[CMP3]]
+; CHECK-NEXT:    br i1 [[CMP3_FROZEN]], label [[SELECT_TRUE_SINK:%.*]], label [[SELECT_END]]
+; CHECK:       select.true.sink:
+; CHECK-NEXT:    [[TMP0:%.*]] = add nsw i64 [[J]], 1
+; CHECK-NEXT:    br label [[SELECT_END]]
+; CHECK:       select.end:
+; CHECK-NEXT:    [[J_NEXT]] = phi i64 [ [[TMP0]], [[SELECT_TRUE_SINK]] ], [ [[J]], [[LOOP]] ]
 ; CHECK-NEXT:    [[GEP_DST:%.*]] = getelementptr inbounds ptr, ptr [[DST:%.*]], i64 [[IV]]
 ; CHECK-NEXT:    store i64 [[J_NEXT]], ptr [[GEP_DST]], align 8
 ; CHECK-NEXT:    [[IV_NEXT]] = add i64 [[IV]], 1
@@ -54,20 +60,26 @@ define void @test_add_zext_first_op(ptr %dst, ptr %src, i64 %j.start, i64 %p, i6
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
-; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
-; CHECK-NEXT:    [[J:%.*]] = phi i64 [ [[J_START:%.*]], [[ENTRY]] ], [ [[J_NEXT:%.*]], [[LOOP]] ]
-; CHECK-NEXT:    [[I:%.*]] = phi i64 [ [[I_START:%.*]], [[ENTRY]] ], [ [[J_NEXT]], [[LOOP]] ]
-; CHECK-NEXT:    [[GEP_I:%.*]] = getelementptr inbounds ptr, ptr [[SRC:%.*]], i64 [[I]]
-; CHECK-NEXT:    [[L_I:%.*]] = load ptr, ptr [[GEP_I]], align 8
-; CHECK-NEXT:    [[GEP_J:%.*]] = getelementptr inbounds ptr, ptr [[SRC]], i64 [[J]]
+; CHECK-NEXT:    [[IV1:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[SELECT_END:%.*]] ]
+; CHECK-NEXT:    [[J:%.*]] = phi i64 [ [[J_START:%.*]], [[ENTRY]] ], [ [[J_NEXT:%.*]], [[SELECT_END]] ]
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ [[I_START:%.*]], [[ENTRY]] ], [ [[J_NEXT]], [[SELECT_END]] ]
+; CHECK-NEXT:    [[GEP_DST:%.*]] = getelementptr inbounds ptr, ptr [[DST:%.*]], i64 [[IV]]
+; CHECK-NEXT:    [[L_I:%.*]] = load ptr, ptr [[GEP_DST]], align 8
+; CHECK-NEXT:    [[GEP_J:%.*]] = getelementptr inbounds ptr, ptr [[DST]], i64 [[J]]
 ; CHECK-NEXT:    [[L_J:%.*]] = load ptr, ptr [[GEP_J]], align 8
 ; CHECK-NEXT:    [[CMP3:%.*]] = icmp ult ptr [[L_I]], [[L_J]]
 ; CHECK-NEXT:    [[DEC:%.*]] = zext i1 [[CMP3]] to i64
-; CHECK-NEXT:    [[J_NEXT]] = add nsw i64 [[DEC]], [[J]]
-; CHECK-NEXT:    [[GEP_DST:%.*]] = getelementptr inbounds ptr, ptr [[DST:%.*]], i64 [[IV]]
-; CHECK-NEXT:    store i64 [[J_NEXT]], ptr [[GEP_DST]], align 8
-; CHECK-NEXT:    [[IV_NEXT]] = add i64 [[IV]], 1
-; CHECK-NEXT:    [[EC:%.*]] = icmp eq i64 [[IV]], [[J_START]]
+; CHECK-NEXT:    [[CMP3_FROZEN:%.*]] = freeze i1 [[CMP3]]
+; CHECK-NEXT:    br i1 [[CMP3_FROZEN]], label [[SELECT_TRUE_SINK:%.*]], label [[SELECT_END]]
+; CHECK:       select.true.sink:
+; CHECK-NEXT:    [[TMP0:%.*]] = add nsw i64 1, [[J]]
+; CHECK-NEXT:    br label [[SELECT_END]]
+; CHECK:       select.end:
+; CHECK-NEXT:    [[J_NEXT]] = phi i64 [ [[TMP0]], [[SELECT_TRUE_SINK]] ], [ [[J]], [[LOOP]] ]
+; CHECK-NEXT:    [[GEP_DST1:%.*]] = getelementptr inbounds ptr, ptr [[DST1:%.*]], i64 [[IV1]]
+; CHECK-NEXT:    store i64 [[J_NEXT]], ptr [[GEP_DST1]], align 8
+; CHECK-NEXT:    [[IV_NEXT]] = add i64 [[IV1]], 1
+; CHECK-NEXT:    [[EC:%.*]] = icmp eq i64 [[IV1]], [[J_START]]
 ; CHECK-NEXT:    br i1 [[EC]], label [[EXIT:%.*]], label [[LOOP]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    ret void
@@ -101,9 +113,9 @@ define void @test_add_zext_not(ptr %dst, ptr %src, i64 %j.start, i64 %p, i64 %i.
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
-; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
-; CHECK-NEXT:    [[J:%.*]] = phi i64 [ [[J_START:%.*]], [[ENTRY]] ], [ [[J_NEXT:%.*]], [[LOOP]] ]
-; CHECK-NEXT:    [[I:%.*]] = phi i64 [ [[I_START:%.*]], [[ENTRY]] ], [ [[J_NEXT]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[SELECT_END:%.*]] ]
+; CHECK-NEXT:    [[J:%.*]] = phi i64 [ [[J_START:%.*]], [[ENTRY]] ], [ [[J_NEXT:%.*]], [[SELECT_END]] ]
+; CHECK-NEXT:    [[I:%.*]] = phi i64 [ [[I_START:%.*]], [[ENTRY]] ], [ [[J_NEXT]], [[SELECT_END]] ]
 ; CHECK-NEXT:    [[GEP_I:%.*]] = getelementptr inbounds ptr, ptr [[SRC:%.*]], i64 [[I]]
 ; CHECK-NEXT:    [[L_I:%.*]] = load ptr, ptr [[GEP_I]], align 8
 ; CHECK-NEXT:    [[GEP_J:%.*]] = getelementptr inbounds ptr, ptr [[SRC]], i64 [[J]]
@@ -111,7 +123,13 @@ define void @test_add_zext_not(ptr %dst, ptr %src, i64 %j.start, i64 %p, i64 %i.
 ; CHECK-NEXT:    [[CMP3:%.*]] = icmp ult ptr [[L_I]], [[L_J]]
 ; CHECK-NEXT:    [[NOT_CMP3:%.*]] = xor i1 [[CMP3]], true
 ; CHECK-NEXT:    [[DEC:%.*]] = zext i1 [[NOT_CMP3]] to i64
-; CHECK-NEXT:    [[J_NEXT]] = add nsw i64 [[J]], [[DEC]]
+; CHECK-NEXT:    [[CMP3_FROZEN:%.*]] = freeze i1 [[CMP3]]
+; CHECK-NEXT:    br i1 [[CMP3_FROZEN]], label [[SELECT_END]], label [[SELECT_FALSE_SINK:%.*]]
+; CHECK:       select.false.sink:
+; CHECK-NEXT:    [[TMP0:%.*]] = add nsw i64 [[J]], 1
+; CHECK-NEXT:    br label [[SELECT_END]]
+; CHECK:       select.end:
+; CHECK-NEXT:    [[J_NEXT]] = phi i64 [ [[J]], [[LOOP]] ], [ [[TMP0]], [[SELECT_FALSE_SINK]] ]
 ; CHECK-NEXT:    [[GEP_DST:%.*]] = getelementptr inbounds ptr, ptr [[DST:%.*]], i64 [[IV]]
 ; CHECK-NEXT:    store i64 [[J_NEXT]], ptr [[GEP_DST]], align 8
 ; CHECK-NEXT:    [[IV_NEXT]] = add i64 [[IV]], 1
@@ -356,16 +374,22 @@ define void @test_sub_zext(ptr %dst, ptr %src, i64 %j.start, i64 %p, i64 %i.star
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
-; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
-; CHECK-NEXT:    [[J:%.*]] = phi i64 [ [[HIGH:%.*]], [[ENTRY]] ], [ [[J_NEXT:%.*]], [[LOOP]] ]
-; CHECK-NEXT:    [[I:%.*]] = phi i64 [ [[I_START:%.*]], [[ENTRY]] ], [ [[J_NEXT]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[SELECT_END:%.*]] ]
+; CHECK-NEXT:    [[J:%.*]] = phi i64 [ [[HIGH:%.*]], [[ENTRY]] ], [ [[J_NEXT:%.*]], [[SELECT_END]] ]
+; CHECK-NEXT:    [[I:%.*]] = phi i64 [ [[I_START:%.*]], [[ENTRY]] ], [ [[J_NEXT]], [[SELECT_END]] ]
 ; CHECK-NEXT:    [[GEP_I:%.*]] = getelementptr inbounds ptr, ptr [[SRC:%.*]], i64 [[I]]
 ; CHECK-NEXT:    [[L_I:%.*]] = load ptr, ptr [[GEP_I]], align 8
 ; CHECK-NEXT:    [[GEP_J:%.*]] = getelementptr inbounds ptr, ptr [[SRC]], i64 [[J]]
 ; CHECK-NEXT:    [[L_J:%.*]] = load ptr, ptr [[GEP_J]], align 8
 ; CHECK-NEXT:    [[CMP3:%.*]] = icmp ult ptr [[L_I]], [[L_J]]
 ; CHECK-NEXT:    [[DEC:%.*]] = zext i1 [[CMP3]] to i64
-; CHECK-NEXT:    [[J_NEXT]] = sub nsw i64 [[J]], [[DEC]]
+; CHECK-NEXT:    [[CMP3_FROZEN:%.*]] = freeze i1 [[CMP3]]
+; CHECK-NEXT:    br i1 [[CMP3_FROZEN]], label [[SELECT_TRUE_SINK:%.*]], label [[SELECT_END]]
+; CHECK:       select.true.sink:
+; CHECK-NEXT:    [[TMP0:%.*]] = sub nsw i64 [[J]], 1
+; CHECK-NEXT:    br label [[SELECT_END]]
+; CHECK:       select.end:
+; CHECK-NEXT:    [[J_NEXT]] = phi i64 [ [[TMP0]], [[SELECT_TRUE_SINK]] ], [ [[J]], [[LOOP]] ]
 ; CHECK-NEXT:    [[GEP_DST:%.*]] = getelementptr inbounds ptr, ptr [[DST:%.*]], i64 [[IV]]
 ; CHECK-NEXT:    store i64 [[J_NEXT]], ptr [[GEP_DST]], align 8
 ; CHECK-NEXT:    [[IV_NEXT]] = add i64 [[IV]], 1
@@ -403,20 +427,26 @@ define void @test_sub_zext_first_op(ptr %dst, ptr %src, i64 %j.start, i64 %p, i6
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
-; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
-; CHECK-NEXT:    [[J:%.*]] = phi i64 [ [[J_START:%.*]], [[ENTRY]] ], [ [[J_NEXT:%.*]], [[LOOP]] ]
-; CHECK-NEXT:    [[I:%.*]] = phi i64 [ [[I_START:%.*]], [[ENTRY]] ], [ [[J_NEXT]], [[LOOP]] ]
-; CHECK-NEXT:    [[GEP_I:%.*]] = getelementptr inbounds ptr, ptr [[SRC:%.*]], i64 [[I]]
-; CHECK-NEXT:    [[L_I:%.*]] = load ptr, ptr [[GEP_I]], align 8
-; CHECK-NEXT:    [[GEP_J:%.*]] = getelementptr inbounds ptr, ptr [[SRC]], i64 [[J]]
+; CHECK-NEXT:    [[IV1:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[SELECT_END:%.*]] ]
+; CHECK-NEXT:    [[J:%.*]] = phi i64 [ [[J_START:%.*]], [[ENTRY]] ], [ [[J_NEXT:%.*]], [[SELECT_END]] ]
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ [[I_START:%.*]], [[ENTRY]] ], [ [[J_NEXT]], [[SELECT_END]] ]
+; CHECK-NEXT:    [[GEP_DST:%.*]] = getelementptr inbounds ptr, ptr [[DST:%.*]], i64 [[IV]]
+; CHECK-NEXT:    [[L_I:%.*]] = load ptr, ptr [[GEP_DST]], align 8
+; CHECK-NEXT:    [[GEP_J:%.*]] = getelementptr inbounds ptr, ptr [[DST]], i64 [[J]]
 ; CHECK-NEXT:    [[L_J:%.*]] = load ptr, ptr [[GEP_J]], align 8
 ; CHECK-NEXT:    [[CMP3:%.*]] = icmp ult ptr [[L_I]], [[L_J]]
 ; CHECK-NEXT:    [[DEC:%.*]] = zext i1 [[CMP3]] to i64
-; CHECK-NEXT:    [[J_NEXT]] = sub nsw i64 [[DEC]], [[J]]
-; CHECK-NEXT:    [[GEP_DST:%.*]] = getelementptr inbounds ptr, ptr [[DST:%.*]], i64 [[IV]]
-; CHECK-NEXT:    store i64 [[J_NEXT]], ptr [[GEP_DST]], align 8
-; CHECK-NEXT:    [[IV_NEXT]] = add i64 [[IV]], 1
-; CHECK-NEXT:    [[EC:%.*]] = icmp eq i64 [[IV]], [[J_START]]
+; CHECK-NEXT:    [[CMP3_FROZEN:%.*]] = freeze i1 [[CMP3]]
+; CHECK-NEXT:    br i1 [[CMP3_FROZEN]], label [[SELECT_TRUE_SINK:%.*]], label [[SELECT_END]]
+; CHECK:       select.true.sink:
+; CHECK-NEXT:    [[TMP0:%.*]] = sub nsw i64 1, [[J]]
+; CHECK-NEXT:    br label [[SELECT_END]]
+; CHECK:       select.end:
+; CHECK-NEXT:    [[J_NEXT]] = phi i64 [ [[TMP0]], [[SELECT_TRUE_SINK]] ], [ [[J]], [[LOOP]] ]
+; CHECK-NEXT:    [[GEP_DST1:%.*]] = getelementptr inbounds ptr, ptr [[DST1:%.*]], i64 [[IV1]]
+; CHECK-NEXT:    store i64 [[J_NEXT]], ptr [[GEP_DST1]], align 8
+; CHECK-NEXT:    [[IV_NEXT]] = add i64 [[IV1]], 1
+; CHECK-NEXT:    [[EC:%.*]] = icmp eq i64 [[IV1]], [[J_START]]
 ; CHECK-NEXT:    br i1 [[EC]], label [[EXIT:%.*]], label [[LOOP]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    ret void
@@ -450,9 +480,9 @@ define void @test_sub_zext_not(ptr %dst, ptr %src, i64 %j.start, i64 %p, i64 %i.
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
-; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP]] ]
-; CHECK-NEXT:    [[J:%.*]] = phi i64 [ [[J_START:%.*]], [[ENTRY]] ], [ [[J_NEXT:%.*]], [[LOOP]] ]
-; CHECK-NEXT:    [[I:%.*]] = phi i64 [ [[I_START:%.*]], [[ENTRY]] ], [ [[J_NEXT]], [[LOOP]] ]
+; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ 0, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[SELECT_END:%.*]] ]
+; CHECK-NEXT:    [[J:%.*]] = phi i64 [ [[J_START:%.*]], [[ENTRY]] ], [ [[J_NEXT:%.*]], [[SELECT_END]] ]
+; CHECK-NEXT:    [[I:%.*]] = phi i64 [ [[I_START:%.*]], [[ENTRY]] ], [ [[J_NEXT]], [[SELECT_END]] ]
 ; CHECK-NEXT:    [[GEP_I:%.*]] = getelementptr inbounds ptr, ptr [[SRC:%.*]], i64 [[I]]
 ; CHECK-NEXT:    [[L_I:%.*]] = load ptr, ptr [[GEP_I]], align 8
 ; CHECK-NEXT:    [[GEP_J:%.*]] = getelementptr inbounds ptr, ptr [[SRC]], i64 [[J]]
@@ -460,7 +490,13 @@ define void @test_sub_zext_not(ptr %dst, ptr %src, i64 %j.start, i64 %p, i64 %i.
 ; CHECK-NEXT:    [[CMP3:%.*]] = icmp ult ptr [[L_I]], [[L_J]]
 ; CHECK-NEXT:    [[NOT_CMP3:%.*]] = xor i1 [[CMP3]], true
 ; CHECK-NEXT:    [[DEC:%.*]] = zext i1 [[NOT_CMP3]] to i64
-; CHECK-NEXT:    [[J_NEXT]] = sub nsw i64 [[J]], [[DEC]]
+; CHECK-NEXT:    [[CMP3_FROZEN:%.*]] = freeze i1 [[CMP3]]
+; CHECK-NEXT:    br i1 [[CMP3_FROZEN]], label [[SELECT_END]], label [[SELECT_FALSE_SINK:%.*]]
+; CHECK:       select.false.sink:
+; CHECK-NEXT:    [[TMP0:%.*]] = sub nsw i64 [[J]], 1
+; CHECK-NEXT:    br label [[SELECT_END]]
+; CHECK:       select.end:
+; CHECK-NEXT:    [[J_NEXT]] = phi i64 [ [[J]], [[LOOP]] ], [ [[TMP0]], [[SELECT_FALSE_SINK]] ]
 ; CHECK-NEXT:    [[GEP_DST:%.*]] = getelementptr inbounds ptr, ptr [[DST:%.*]], i64 [[IV]]
 ; CHECK-NEXT:    store i64 [[J_NEXT]], ptr [[GEP_DST]], align 8
 ; CHECK-NEXT:    [[IV_NEXT]] = add i64 [[IV]], 1


        


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