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

llvm-svn: 173093

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index 03be8ef..c6d60d6 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/llvm/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/llvm/test/Transforms/InstCombine/mul.ll b/llvm/test/Transforms/InstCombine/mul.ll
index bbc70fe..34ce088 100644 (file)
--- a/llvm/test/Transforms/InstCombine/mul.ll
+++ b/llvm/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/llvm/test/Transforms/InstCombine/sext.ll b/llvm/test/Transforms/InstCombine/sext.ll
index f198797..968f37c 100644 (file)
--- a/llvm/test/Transforms/InstCombine/sext.ll
+++ b/llvm/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/llvm/test/Transforms/InstCombine/zext-bool-add-sub.ll b/llvm/test/Transforms/InstCombine/zext-bool-add-sub.ll
index 78bcedb..b531057 100644 (file)
--- a/llvm/test/Transforms/InstCombine/zext-bool-add-sub.ll
+++ b/llvm/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