[PATCH] D137031: [InstCombine] Avoid deleting volatile memcpys.

[Patrick Walton via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rGcb2cb2d20181: [InstCombine] Avoid deleting volatile memcpys. (authored by pcwalton).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D137031/new/

https://reviews.llvm.org/D137031

Files:
  llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
  llvm/test/Transforms/InstCombine/memcpy-from-global.ll


Index: llvm/test/Transforms/InstCombine/memcpy-from-global.ll
===================================================================
--- llvm/test/Transforms/InstCombine/memcpy-from-global.ll
+++ llvm/test/Transforms/InstCombine/memcpy-from-global.ll
@@ -366,10 +366,12 @@
   ret void
 }
 
-; FIXME: Test that we incorrectly elide a volatile memcpy.
+; Test that we don't elide a volatile memcpy.
 define void @volatile_memcpy() {
 ; CHECK-LABEL: @volatile_memcpy(
-; CHECK-NEXT:    call void @bar(ptr nonnull @H) #[[ATTR3]]
+; CHECK-NEXT:    [[A:%.*]] = alloca [[U:%.*]], align 16
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr align 4 [[A]], ptr align 4 @H, i64 20, i1 true)
+; CHECK-NEXT:    call void @bar(ptr nonnull [[A]]) #[[ATTR3]]
 ; CHECK-NEXT:    ret void
 ;
   %A = alloca %U, align 16
Index: llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -111,12 +111,14 @@
       if (!MI)
         return false;
 
+      // If the transfer is volatile, reject it.
+      if (MI->isVolatile())
+        return false;
+
       // If the transfer is using the alloca as a source of the transfer, then
       // ignore it since it is a load (unless the transfer is volatile).
-      if (U.getOperandNo() == 1) {
-        if (MI->isVolatile()) return false;
+      if (U.getOperandNo() == 1)
         continue;
-      }
 
       // If we already have seen a copy, reject the second one.
       if (TheCopy) return false;


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