[llvm-commits] [llvm] r164641 - in /llvm/trunk: lib/Transforms/Scalar/SROA.cpp test/Transforms/SROA/basictest.ll

[Nick Lewycky]

Author: nicholas
Date: Tue Sep 25 17:46:21 2012
New Revision: 164641

URL: http://llvm.org/viewvc/llvm-project?rev=164641&view=rev
Log:
Don't drop the alignment on a memcpy intrinsic when producing a store. This is
only a missed optimization opportunity if the store is over-aligned, but a
miscompile if the store's new type has a higher natural alignment than the
memcpy did. Fixes PR13920!

Modified:
    llvm/trunk/lib/Transforms/Scalar/SROA.cpp
    llvm/trunk/test/Transforms/SROA/basictest.ll

Modified: llvm/trunk/lib/Transforms/Scalar/SROA.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SROA.cpp?rev=164641&r1=164640&r2=164641&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SROA.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SROA.cpp Tue Sep 25 17:46:21 2012
@@ -2272,8 +2272,9 @@
                                     getName(".insert"));
     }
 
-    Value *Store = IRB.CreateStore(Src, DstPtr, II.isVolatile());
-    (void)Store;
+    StoreInst *Store = cast<StoreInst>(IRB.CreateStore(Src, DstPtr,
+                                                       II.isVolatile()));
+    Store->setAlignment(II.getAlignment());
     DEBUG(dbgs() << "          to: " << *Store << "\n");
     return !II.isVolatile();
   }

Modified: llvm/trunk/test/Transforms/SROA/basictest.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SROA/basictest.ll?rev=164641&r1=164640&r2=164641&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SROA/basictest.ll (original)
+++ llvm/trunk/test/Transforms/SROA/basictest.ll Tue Sep 25 17:46:21 2012
@@ -863,6 +863,7 @@
 ; CHECK-NOT: alloca
 ; CHECK: ret void
 ; PR13916
+
 entry:
   %A = alloca %test22.struct
   br i1 undef, label %if.then, label %if.end
@@ -877,3 +878,18 @@
   %tmp2 = load %test22.struct* %A
   ret void
 }
+
+define void @test23(<2 x i64> %a, i16* %b) {
+; CHECK: @test23
+; CHECK: store {{.*}}, align 2
+; CHECK: ret void
+; PR13920
+
+entry:
+  %a.addr = alloca <2 x i64>, align 16
+  store <2 x i64> %a, <2 x i64>* %a.addr, align 16
+  %0 = bitcast i16* %b to i8*
+  %1 = bitcast <2 x i64>* %a.addr to i8*
+  call void @llvm.memcpy.p0i8.p0i8.i32(i8* %0, i8* %1, i32 16, i32 2, i1 false)
+  ret void
+}