[llvm] cba0ebd - Revert "[InstCombine] fold icmp with sub and bool"

[Sanjay Patel via llvm-commits]

Author: Sanjay Patel
Date: 2022-05-22T12:13:20-04:00
New Revision: cba0ebd576228d11817181a9ebc53a1931bb972b

URL: https://github.com/llvm/llvm-project/commit/cba0ebd576228d11817181a9ebc53a1931bb972b
DIFF: https://github.com/llvm/llvm-project/commit/cba0ebd576228d11817181a9ebc53a1931bb972b.diff

LOG: Revert "[InstCombine] fold icmp with sub and bool"

This reverts commit 4069cccf3b4ff4afb743d3d371ead9e2d5491e3a.
This causes bot failures, and there's a possibly a better way to get this and other patterns.

Added: 
    

Modified: 
    llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
    llvm/test/Transforms/InstCombine/icmp-range.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index e2a6b6b1495b8..4f20a0699ec50 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -5631,29 +5631,6 @@ Instruction *InstCombinerImpl::foldICmpUsingKnownBits(ICmpInst &I) {
   return nullptr;
 }
 
-/// If one operand of an icmp is effectively a bool (value range of {0,1}),
-/// then try to reduce patterns based on that limit.
-static Instruction *foldICmpUsingBoolRange(ICmpInst &I,
-                                           InstCombiner::BuilderTy &Builder) {
-  Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
-  const ICmpInst::Predicate Pred = I.getPredicate();
-
-  Value *X, *Y, *Z;
-  if (Pred != ICmpInst::ICMP_ULT || !match(Op0, m_Sub(m_Value(X), m_Value(Y))))
-    return nullptr;
-
-  unsigned ExtraUses = !Op0->hasOneUse() + !Op1->hasOneUse();
-
-  // Sub must be 0 and bool must be true for "ULT":
-  // (sub X, Y) <u (zext i1 Z) --> (X == Y) && Z
-  if (match(Op1, m_ZExt(m_Value(Z))) && ExtraUses < 2) {
-    Value *EqXY = Builder.CreateICmpEQ(X, Y);
-    return BinaryOperator::CreateAnd(EqXY, Z);
-  }
-
-  return nullptr;
-}
-
 llvm::Optional<std::pair<CmpInst::Predicate, Constant *>>
 InstCombiner::getFlippedStrictnessPredicateAndConstant(CmpInst::Predicate Pred,
                                                        Constant *C) {
@@ -6081,9 +6058,6 @@ Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I) {
   if (Instruction *Res = foldICmpWithDominatingICmp(I))
     return Res;
 
-  if (Instruction *Res = foldICmpUsingBoolRange(I, Builder))
-    return Res;
-
   if (Instruction *Res = foldICmpUsingKnownBits(I))
     return Res;
 

diff  --git a/llvm/test/Transforms/InstCombine/icmp-range.ll b/llvm/test/Transforms/InstCombine/icmp-range.ll
index a29d4cd81b9d1..b67356675eba6 100644
--- a/llvm/test/Transforms/InstCombine/icmp-range.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-range.ll
@@ -173,8 +173,9 @@ define i1 @test_two_ranges3(i32* nocapture readonly %arg1, i32* nocapture readon
 
 define i1 @sub_ult_zext(i1 %b, i8 %x, i8 %y) {
 ; CHECK-LABEL: @sub_ult_zext(
-; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i8 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = and i1 [[TMP1]], [[B:%.*]]
+; CHECK-NEXT:    [[Z:%.*]] = zext i1 [[B:%.*]] to i8
+; CHECK-NEXT:    [[S:%.*]] = sub i8 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = icmp ult i8 [[S]], [[Z]]
 ; CHECK-NEXT:    ret i1 [[R]]
 ;
   %z = zext i1 %b to i8
@@ -187,8 +188,8 @@ define i1 @sub_ult_zext_use1(i1 %b, i8 %x, i8 %y) {
 ; CHECK-LABEL: @sub_ult_zext_use1(
 ; CHECK-NEXT:    [[Z:%.*]] = zext i1 [[B:%.*]] to i8
 ; CHECK-NEXT:    call void @use(i8 [[Z]])
-; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i8 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT:    [[R:%.*]] = and i1 [[TMP1]], [[B]]
+; CHECK-NEXT:    [[S:%.*]] = sub i8 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = icmp ult i8 [[S]], [[Z]]
 ; CHECK-NEXT:    ret i1 [[R]]
 ;
   %z = zext i1 %b to i8
@@ -200,10 +201,10 @@ define i1 @sub_ult_zext_use1(i1 %b, i8 %x, i8 %y) {
 
 define <2 x i1> @zext_ugt_sub_use2(<2 x i1> %b, <2 x i8> %x, <2 x i8> %y) {
 ; CHECK-LABEL: @zext_ugt_sub_use2(
+; CHECK-NEXT:    [[Z:%.*]] = zext <2 x i1> [[B:%.*]] to <2 x i8>
 ; CHECK-NEXT:    [[S:%.*]] = sub <2 x i8> [[X:%.*]], [[Y:%.*]]
 ; CHECK-NEXT:    call void @use_vec(<2 x i8> [[S]])
-; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq <2 x i8> [[X]], [[Y]]
-; CHECK-NEXT:    [[R:%.*]] = and <2 x i1> [[TMP1]], [[B:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = icmp ult <2 x i8> [[S]], [[Z]]
 ; CHECK-NEXT:    ret <2 x i1> [[R]]
 ;
   %z = zext <2 x i1> %b to <2 x i8>
@@ -213,8 +214,6 @@ define <2 x i1> @zext_ugt_sub_use2(<2 x i1> %b, <2 x i8> %x, <2 x i8> %y) {
   ret <2 x i1> %r
 }
 
-; negative test - too many extra uses
-
 define i1 @sub_ult_zext_use3(i1 %b, i8 %x, i8 %y) {
 ; CHECK-LABEL: @sub_ult_zext_use3(
 ; CHECK-NEXT:    [[Z:%.*]] = zext i1 [[B:%.*]] to i8
@@ -232,8 +231,6 @@ define i1 @sub_ult_zext_use3(i1 %b, i8 %x, i8 %y) {
   ret i1 %r
 }
 
-; negative test - wrong predicate
-
 define i1 @sub_ule_zext(i1 %b, i8 %x, i8 %y) {
 ; CHECK-LABEL: @sub_ule_zext(
 ; CHECK-NEXT:    [[Z:%.*]] = zext i1 [[B:%.*]] to i8