Transform (sub 0, (zext bool to A)) to (sext bool to A) and

(sub 0, (sext bool to A)) to (zext bool to A).

Patch by Muhammad Ahmad
Reviewed by Duncan Sands

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173093 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index 03be8ef6fb707c2c26a3b0c5c7d427616b3ac53d..c6d60d6f008b87d0d8b2838b47f66c5856f20353 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -1250,6 +1250,16 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
 
     if (SimplifyDemandedInstructionBits(I))
       return &I;
+
+    // Fold (sub 0, (zext bool to B)) --> (sext bool to B)
+    if (C->isZero() && match(Op1, m_ZExt(m_Value(X))))
+      if (X->getType()->isIntegerTy(1))
+        return CastInst::CreateSExtOrBitCast(X, Op1->getType());
+
+    // Fold (sub 0, (sext bool to B)) --> (zext bool to B)
+    if (C->isZero() && match(Op1, m_SExt(m_Value(X))))
+      if (X->getType()->isIntegerTy(1))
+        return CastInst::CreateZExtOrBitCast(X, Op1->getType());
   }
 
 

diff --git a/test/Transforms/InstCombine/mul.ll b/test/Transforms/InstCombine/mul.ll
index bbc70fe33349d9919bd8e316a47bcb349c5028f5..34ce088e2936c8e93d1076a542936fe3bca09585 100644 (file)
--- a/test/Transforms/InstCombine/mul.ll
+++ b/test/Transforms/InstCombine/mul.ll
@@ -138,8 +138,7 @@ define i32 @test16(i32 %b, i1 %c) {
         ; e = b & (a >> 31)
         %e = mul i32 %d, %b             ; <i32> [#uses=1]
         ret i32 %e
-; CHECK: [[TEST16:%.*]] = zext i1 %c to i32
-; CHECK-NEXT: %1 = sub i32 0, [[TEST16]]
+; CHECK: [[TEST16:%.*]] = sext i1 %c to i32
 ; CHECK-NEXT: %e = and i32 %1, %b
 ; CHECK-NEXT: ret i32 %e
 }

diff --git a/test/Transforms/InstCombine/sext.ll b/test/Transforms/InstCombine/sext.ll
index f1987973f4622664426d4aec960a0584d9984d62..968f37c9c129ea946fe27095cb5d2c033fae035f 100644 (file)
--- a/test/Transforms/InstCombine/sext.ll
+++ b/test/Transforms/InstCombine/sext.ll
@@ -184,3 +184,12 @@ define i32 @test16(i16 %x) nounwind {
 ; CHECK-NEXT: %ext = sext i16 %sext to i32
 ; CHECK-NEXT: ret i32 %ext
 }
+
+define i32 @test17(i1 %x) nounwind {
+  %c1 = sext i1 %x to i32
+  %c2 = sub i32 0, %c1
+  ret i32 %c2
+; CHECK: @test17
+; CHECK-NEXT: [[TEST17:%.*]] = zext i1 %x to i32
+; CHECK-NEXT: ret i32 [[TEST17]]
+}

diff --git a/test/Transforms/InstCombine/zext-bool-add-sub.ll b/test/Transforms/InstCombine/zext-bool-add-sub.ll
index 78bcedbbc2e1a43a32f63c9cfcd339d379a0d6c9..b5310575502bd96284ad12d63190bcb3a12cd865 100644 (file)
--- a/test/Transforms/InstCombine/zext-bool-add-sub.ll
+++ b/test/Transforms/InstCombine/zext-bool-add-sub.ll
@@ -4,9 +4,9 @@
 define i32 @a(i1 zeroext %x, i1 zeroext %y) {
 entry:
 ; CHECK: @a
-; CHECK: [[TMP1:%.*]] = zext i1 %y to i32
+; CHECK: [[TMP1:%.*]] = sext i1 %y to i32
 ; CHECK: [[TMP2:%.*]] = select i1 %x, i32 2, i32 1
-; CHECK-NEXT: sub i32 [[TMP2]], [[TMP1]]
+; CHECK-NEXT: add i32 [[TMP2]], [[TMP1]]
   %conv = zext i1 %x to i32
   %conv3 = zext i1 %y to i32
   %conv3.neg = sub i32 0, %conv3