InstCombine: Preserve nsw when folding X*(2^C) -> X << C

llvm-svn: 222606

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 7844223..5ea25bf 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -179,6 +179,8 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) {
 
         if (I.hasNoUnsignedWrap())
           Shl->setHasNoUnsignedWrap();
+        if (I.hasNoSignedWrap() && NewCst->isNotMinSignedValue())
+          Shl->setHasNoSignedWrap();
 
         return Shl;
       }

diff --git a/llvm/test/Transforms/InstCombine/add2.ll b/llvm/test/Transforms/InstCombine/add2.ll
index a166e5f..2a63082 100644 (file)
--- a/llvm/test/Transforms/InstCombine/add2.ll
+++ b/llvm/test/Transforms/InstCombine/add2.ll
@@ -219,7 +219,7 @@ define i16 @mul_add_to_mul_1(i16 %x) {
  %add2 = add nsw i16 %x, %mul1
  ret i16 %add2
 ; CHECK-LABEL: @mul_add_to_mul_1(
-; CHECK-NEXT: %add2 = mul i16 %x, 9
+; CHECK-NEXT: %add2 = mul nsw i16 %x, 9
 ; CHECK-NEXT: ret i16 %add2
 }
 
@@ -228,7 +228,7 @@ define i16 @mul_add_to_mul_2(i16 %x) {
  %add2 = add nsw i16 %mul1, %x
  ret i16 %add2
 ; CHECK-LABEL: @mul_add_to_mul_2(
-; CHECK-NEXT: %add2 = mul i16 %x, 9
+; CHECK-NEXT: %add2 = mul nsw i16 %x, 9
 ; CHECK-NEXT: ret i16 %add2
 }
 
@@ -248,7 +248,7 @@ define i16 @mul_add_to_mul_4(i16 %a) {
  %add = add nsw i16 %mul1, %mul2
  ret i16 %add
 ; CHECK-LABEL: @mul_add_to_mul_4(
-; CHECK-NEXT: %add = mul i16 %a, 9
+; CHECK-NEXT: %add = mul nsw i16 %a, 9
 ; CHECK-NEXT: ret i16 %add
 }
 

diff --git a/llvm/test/Transforms/InstCombine/div.ll b/llvm/test/Transforms/InstCombine/div.ll
index 2841043..5af8668 100644 (file)
--- a/llvm/test/Transforms/InstCombine/div.ll
+++ b/llvm/test/Transforms/InstCombine/div.ll
@@ -217,7 +217,7 @@ define i32 @test25(i32 %a) {
   %div = sdiv i32 %shl, 2
   ret i32 %div
 ; CHECK-LABEL: @test25(
-; CHECK-NEXT: %div = shl i32 %a, 1
+; CHECK-NEXT: %div = shl nsw i32 %a, 1
 ; CHECK-NEXT: ret i32 %div
 }
 
@@ -226,7 +226,7 @@ define i32 @test26(i32 %a) {
   %div = sdiv i32 %mul, 3
   ret i32 %div
 ; CHECK-LABEL: @test26(
-; CHECK-NEXT: %div = shl i32 %a, 2
+; CHECK-NEXT: %div = shl nsw i32 %a, 2
 ; CHECK-NEXT: ret i32 %div
 }