[llvm] 6643e51 - [InstCombine] Fold (sext bool X) * (sext bool X) to zext (and X, X)

[Daniil Seredkin via llvm-commits]

Author: Daniil Seredkin
Date: 2021-06-18T16:28:06+07:00
New Revision: 6643e51d79d776efc3f4469b6f90b73c71a8fc41

URL: https://github.com/llvm/llvm-project/commit/6643e51d79d776efc3f4469b6f90b73c71a8fc41
DIFF: https://github.com/llvm/llvm-project/commit/6643e51d79d776efc3f4469b6f90b73c71a8fc41.diff

LOG: [InstCombine] Fold (sext bool X) * (sext bool X) to zext (and X, X)

InstCombine didn't perform (sext bool X) * (sext bool X) --> zext (and X, X) which can result in just (zext X). The patch adds regression tests to check this transformation and adds a check for equality of mul's operands for that case.

Differential Revision: https://reviews.llvm.org/D104193

Added: 
    

Modified: 
    llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
    llvm/test/Transforms/InstCombine/mul.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 4e7b8d0ddb341..6f2a8ebf839a7 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -328,7 +328,7 @@ Instruction *InstCombinerImpl::visitMul(BinaryOperator &I) {
   if (((match(Op0, m_ZExt(m_Value(X))) && match(Op1, m_ZExt(m_Value(Y)))) ||
        (match(Op0, m_SExt(m_Value(X))) && match(Op1, m_SExt(m_Value(Y))))) &&
       X->getType()->isIntOrIntVectorTy(1) && X->getType() == Y->getType() &&
-      (Op0->hasOneUse() || Op1->hasOneUse())) {
+      (Op0->hasOneUse() || Op1->hasOneUse() || X == Y)) {
     Value *And = Builder.CreateAnd(X, Y, "mulbool");
     return CastInst::Create(Instruction::ZExt, And, I.getType());
   }

diff  --git a/llvm/test/Transforms/InstCombine/mul.ll b/llvm/test/Transforms/InstCombine/mul.ll
index 8a279f1e10347..15faf764a0404 100644
--- a/llvm/test/Transforms/InstCombine/mul.ll
+++ b/llvm/test/Transforms/InstCombine/mul.ll
@@ -261,8 +261,7 @@ define i32 @mul_bools_sext_one_use_per_op(i1 %x, i1 %y) {
 
 define i32 @mul_bool_sext_one_user(i1 %x) {
 ; CHECK-LABEL: @mul_bool_sext_one_user(
-; CHECK-NEXT:    [[SX:%.*]] = sext i1 [[X:%.*]] to i32
-; CHECK-NEXT:    [[R:%.*]] = mul nsw i32 [[SX]], [[SX]]
+; CHECK-NEXT:    [[R:%.*]] = zext i1 [[X:%.*]] to i32
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %sx = sext i1 %x to i32
@@ -296,7 +295,7 @@ define i32 @mul_bool_sext_one_extra_user(i1 %x) {
 ; CHECK-LABEL: @mul_bool_sext_one_extra_user(
 ; CHECK-NEXT:    [[SX:%.*]] = sext i1 [[X:%.*]] to i32
 ; CHECK-NEXT:    call void @use32(i32 [[SX]])
-; CHECK-NEXT:    [[R:%.*]] = mul nsw i32 [[SX]], [[SX]]
+; CHECK-NEXT:    [[R:%.*]] = zext i1 [[X]] to i32
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %sx = sext i1 %x to i32