[llvm] r280072 - [SimplifyCFG] Properly CSE metadata in SinkThenElseCodeToEnd

[James Molloy via llvm-commits]

Author: jamesm
Date: Tue Aug 30 05:56:08 2016
New Revision: 280072

URL: http://llvm.org/viewvc/llvm-project?rev=280072&view=rev
Log:
[SimplifyCFG] Properly CSE metadata in SinkThenElseCodeToEnd

This was missing, meaning the metadata in sunk instructions was potentially bogus and could cause miscompiles.

Modified:
    llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
    llvm/trunk/test/Transforms/SimplifyCFG/sink-common-code.ll

Modified: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp?rev=280072&r1=280071&r2=280072&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Tue Aug 30 05:56:08 2016
@@ -1533,6 +1533,11 @@ static void sinkLastInstruction(ArrayRef
     I0->getOperandUse(O).set(NewOperands[O]);
   I0->moveBefore(&*BBEnd->getFirstInsertionPt());
 
+  // Update metadata.
+  for (auto *I : Insts)
+    if (I != I0)
+      combineMetadataForCSE(I0, I);
+
   if (!isa<StoreInst>(I0)) {
     // canSinkLastInstruction checked that all instructions were used by
     // one and only one PHI node. Find that now, RAUW it to our common

Modified: llvm/trunk/test/Transforms/SimplifyCFG/sink-common-code.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/sink-common-code.ll?rev=280072&r1=280071&r2=280072&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SimplifyCFG/sink-common-code.ll (original)
+++ llvm/trunk/test/Transforms/SimplifyCFG/sink-common-code.ll Tue Aug 30 05:56:08 2016
@@ -310,3 +310,40 @@ declare i32 @llvm.cttz.i32(i32 %x) readn
 ; CHECK: call i32 @llvm.ctlz
 ; CHECK: call i32 @llvm.cttz
 
+; The TBAA metadata should be properly combined.
+define i32 @test13(i1 zeroext %flag, i32 %x, i32* %y) {
+entry:
+  br i1 %flag, label %if.then, label %if.else
+
+if.then:
+  %z = load volatile i32, i32* %y
+  %a = add i32 %z, 5
+  store volatile i32 %a, i32* %y, !tbaa !3
+  br label %if.end
+
+if.else:
+  %w = load volatile i32, i32* %y
+  %b = add i32 %w, 7
+  store volatile i32 %b, i32* %y, !tbaa !4
+  br label %if.end
+
+if.end:
+  ret i32 1
+}
+
+!0 = !{ !"an example type tree" }
+!1 = !{ !"int", !0 }
+!2 = !{ !"float", !0 }
+!3 = !{ !"const float", !2, i64 0 }
+!4 = !{ !"special float", !2, i64 1 }
+
+; CHECK-LABEL: test13
+; CHECK-DAG: select
+; CHECK-DAG: load volatile
+; CHECK: store volatile {{.*}}, !tbaa !0
+; CHECK-NOT: load
+; CHECK-NOT: store
+
+; CHECK: !0 = !{!1, !1, i64 0}
+; CHECK: !1 = !{!"float", !2}
+; CHECK: !2 = !{!"an example type tree"}
\ No newline at end of file