[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

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 4e7b8d0..6f2a8eb 100644 (file)
--- 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 8a279f1..b3b9476 100644 (file)
--- a/llvm/test/Transforms/InstCombine/mul.ll
+++ b/llvm/test/Transforms/InstCombine/mul.ll
@@ -318,6 +318,76 @@ define i32 @mul_bool_zext_one_extra_user(i1 %x) {
   ret i32 %r
 }
 
+define i32 @mul_bools_sext_one_use_per_op(i1 %x, i1 %y) {
+; CHECK-LABEL: @mul_bools_sext_one_use_per_op(
+; CHECK-NEXT:    [[MULBOOL:%.*]] = and i1 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = zext i1 [[MULBOOL]] to i32
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %sx = sext i1 %x to i32
+  %sy = sext i1 %y to i32
+  %r = mul i32 %sx, %sy
+  ret i32 %r
+}
+
+define i32 @mul_bool_sext_one_user(i1 %x) {
+; CHECK-LABEL: @mul_bool_sext_one_user(
+; CHECK-NEXT:    [[R:%.*]] = zext i1 [[X:%.*]] to i32
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %sx = sext i1 %x to i32
+  %r = mul i32 %sx, %sx
+  ret i32 %r
+}
+
+define i32 @mul_bools_zext_one_use_per_op(i1 %x, i1 %y) {
+; CHECK-LABEL: @mul_bools_zext_one_use_per_op(
+; CHECK-NEXT:    [[MULBOOL:%.*]] = and i1 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = zext i1 [[MULBOOL]] to i32
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %zx = zext i1 %x to i32
+  %zy = zext i1 %y to i32
+  %r = mul i32 %zx, %zy
+  ret i32 %r
+}
+
+define i32 @mul_bool_zext_one_user(i1 %x) {
+; CHECK-LABEL: @mul_bool_zext_one_user(
+; CHECK-NEXT:    [[R:%.*]] = zext i1 [[X:%.*]] to i32
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %sx = zext i1 %x to i32
+  %r = mul i32 %sx, %sx
+  ret i32 %r
+}
+
+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:%.*]] = zext i1 [[X]] to i32
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %sx = sext i1 %x to i32
+  call void @use32(i32 %sx)
+  %r = mul i32 %sx, %sx
+  ret i32 %r
+}
+
+define i32 @mul_bool_zext_one_extra_user(i1 %x) {
+; CHECK-LABEL: @mul_bool_zext_one_extra_user(
+; CHECK-NEXT:    [[SX:%.*]] = zext i1 [[X:%.*]] to i32
+; CHECK-NEXT:    call void @use32(i32 [[SX]])
+; CHECK-NEXT:    [[R:%.*]] = zext i1 [[X]] to i32
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %sx = zext i1 %x to i32
+  call void @use32(i32 %sx)
+  %r = mul i32 %sx, %sx
+  ret i32 %r
+}
+
 define <3 x i32> @mul_bools_mixed_ext(<3 x i1> %x, <3 x i1> %y) {
 ; CHECK-LABEL: @mul_bools_mixed_ext(
 ; CHECK-NEXT:    [[MULBOOL:%.*]] = and <3 x i1> [[X:%.*]], [[Y:%.*]]