[PATCH] D60396: [InstCombine] sdiv exact flag fixup

[ChenZheng via Phabricator via llvm-commits]

shchenz updated this revision to Diff 194107.
shchenz added a comment.

address Roman's comments.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D60396/new/

https://reviews.llvm.org/D60396

Files:
  llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
  llvm/test/Transforms/InstCombine/div.ll


Index: llvm/test/Transforms/InstCombine/div.ll
===================================================================
--- llvm/test/Transforms/InstCombine/div.ll
+++ llvm/test/Transforms/InstCombine/div.ll
@@ -762,7 +762,7 @@
 
 define i32 @test_exact_nsw_exact(i32 %x) {
 ; CHECK-LABEL: @test_exact_nsw_exact(
-; CHECK-NEXT:    [[NEG:%.*]] = sdiv i32 [[X:%.*]], -3
+; CHECK-NEXT:    [[NEG:%.*]] = sdiv exact i32 [[X:%.*]], -3
 ; CHECK-NEXT:    ret i32 [[NEG]]
 ;
   %div = sdiv exact i32 %x, 3
@@ -772,7 +772,7 @@
 
 define <2 x i64> @test_exact_vec(<2 x i64> %x) {
 ; CHECK-LABEL: @test_exact_vec(
-; CHECK-NEXT:    [[NEG:%.*]] = sdiv <2 x i64> [[X:%.*]], <i64 -3, i64 -4>
+; CHECK-NEXT:    [[NEG:%.*]] = sdiv exact <2 x i64> [[X:%.*]], <i64 -3, i64 -4>
 ; CHECK-NEXT:    ret <2 x i64> [[NEG]]
 ;
   %div = sdiv exact <2 x i64> %x, <i64 3, i64 4>
@@ -782,7 +782,7 @@
 
 define i32 @test_exact_nonsw_exact(i32 %x) {
 ; CHECK-LABEL: @test_exact_nonsw_exact(
-; CHECK-NEXT:    [[NEG:%.*]] = sdiv i32 [[X:%.*]], -3
+; CHECK-NEXT:    [[NEG:%.*]] = sdiv exact i32 [[X:%.*]], -3
 ; CHECK-NEXT:    ret i32 [[NEG]]
 ;
   %div = sdiv exact i32 %x, 3
Index: llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -1693,8 +1693,11 @@
 
     // 0 - (X sdiv C)  -> (X sdiv -C)  provided the negation doesn't overflow.
     if (match(Op1, m_SDiv(m_Value(X), m_Constant(C))) && match(Op0, m_Zero()) &&
-        C->isNotMinSignedValue() && !C->isOneValue())
-      return BinaryOperator::CreateSDiv(X, ConstantExpr::getNeg(C));
+        C->isNotMinSignedValue() && !C->isOneValue()) {
+      auto *BO = BinaryOperator::CreateSDiv(X, ConstantExpr::getNeg(C));
+      BO->setIsExact(cast<BinaryOperator>(Op1)->isExact());
+      return BO;
+    }
 
     // 0 - (X << Y)  -> (-X << Y)   when X is freely negatable.
     if (match(Op1, m_Shl(m_Value(X), m_Value(Y))) && match(Op0, m_Zero()))


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D60396.194107.patch
Type: text/x-patch
Size: 2056 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20190408/93b5bd6b/attachment.bin>