[PATCH] D47576: [InstCombine] Fix div handling

[Serguei Katkov via Phabricator via llvm-commits]

skatkov updated this revision to Diff 149388.
skatkov added a comment.

Please take a look.


https://reviews.llvm.org/D47576

Files:
  lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
  test/Transforms/InstCombine/sdiv-guard.ll


Index: test/Transforms/InstCombine/sdiv-guard.ll
===================================================================
--- /dev/null
+++ test/Transforms/InstCombine/sdiv-guard.ll
@@ -0,0 +1,22 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+declare void @llvm.experimental.guard(i1, ...)
+
+; Regression test. If %flag is false then %s == 0 and guard should be triggered.
+define i32 @a(i1 %flag, i32 %X) nounwind readnone {
+; CHECK-LABEL: @a(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp ne i32 [[X:%.*]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = and i1 [[CMP1]], [[FLAG:%.*]]
+; CHECK-NEXT:    call void (i1, ...) @llvm.experimental.guard(i1 [[CMP]]) #1 [ "deopt"() ]
+; CHECK-NEXT:    [[R:%.*]] = sdiv i32 100, [[X]]
+; CHECK-NEXT:    ret i32 [[R]]
+;
+entry:
+  %s = select i1 %flag, i32 %X, i32 0
+  %cmp = icmp ne i32 %s, 0
+  call void(i1, ...) @llvm.experimental.guard( i1 %cmp )[ "deopt"() ]
+  %r = sdiv i32 100, %s
+  ret i32 %r
+}
Index: lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -583,9 +583,9 @@
   Type *CondTy = SelectCond->getType();
   while (BBI != BBFront) {
     --BBI;
-    // If we found a call to a function, we can't assume it will return, so
+    // If we found an instruction that we can't assume it will return, so
     // information from below it cannot be propagated above it.
-    if (isa<CallInst>(BBI) && !isa<IntrinsicInst>(BBI))
+    if (!isGuaranteedToTransferExecutionToSuccessor(&*BBI))
       break;
 
     // Replace uses of the select or its condition with the known values.


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