[llvm] r189785 - [msan] Fix select instrumentation.

[Evgeniy Stepanov]

Author: eugenis
Date: Tue Sep  3 05:04:11 2013
New Revision: 189785

URL: http://llvm.org/viewvc/llvm-project?rev=189785&view=rev
Log:
[msan] Fix select instrumentation.

Select condition shadow was being ignored resulting in false negatives.
This change OR-s sign-extended condition shadow into the result shadow.

Modified:
    llvm/trunk/lib/Transforms/Instrumentation/MemorySanitizer.cpp
    llvm/trunk/test/Instrumentation/MemorySanitizer/msan_basic.ll

Modified: llvm/trunk/lib/Transforms/Instrumentation/MemorySanitizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Instrumentation/MemorySanitizer.cpp?rev=189785&r1=189784&r2=189785&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/MemorySanitizer.cpp (original)
+++ llvm/trunk/lib/Transforms/Instrumentation/MemorySanitizer.cpp Tue Sep  3 05:04:11 2013
@@ -1743,9 +1743,12 @@ struct MemorySanitizerVisitor : public I
 
   void visitSelectInst(SelectInst& I) {
     IRBuilder<> IRB(&I);
-    setShadow(&I,  IRB.CreateSelect(I.getCondition(),
-              getShadow(I.getTrueValue()), getShadow(I.getFalseValue()),
-              "_msprop"));
+    // a = select b, c, d
+    // Sa = (sext Sb) | (select b, Sc, Sd)
+    Value *S = IRB.CreateSelect(I.getCondition(), getShadow(I.getTrueValue()),
+                                getShadow(I.getFalseValue()));
+    Value *S2 = IRB.CreateSExt(getShadow(I.getCondition()), S->getType());
+    setShadow(&I, IRB.CreateOr(S, S2, "_msprop"));
     if (MS.TrackOrigins) {
       // Origins are always i32, so any vector conditions must be flattened.
       // FIXME: consider tracking vector origins for app vectors?

Modified: llvm/trunk/test/Instrumentation/MemorySanitizer/msan_basic.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Instrumentation/MemorySanitizer/msan_basic.ll?rev=189785&r1=189784&r2=189785&view=diff
==============================================================================
--- llvm/trunk/test/Instrumentation/MemorySanitizer/msan_basic.ll (original)
+++ llvm/trunk/test/Instrumentation/MemorySanitizer/msan_basic.ll Tue Sep  3 05:04:11 2013
@@ -260,6 +260,8 @@ entry:
 
 ; CHECK: @Select
 ; CHECK: select
+; CHECK-NEXT: sext i1 {{.*}} to i32
+; CHECK-NEXT: or i32
 ; CHECK-NEXT: select
 ; CHECK: ret i32
 
@@ -274,6 +276,13 @@ entry:
   ret <8 x i16> %cond
 }
 
+; CHECK: @SelectVector
+; CHECK: select <8 x i1>
+; CHECK-NEXT: sext <8 x i1> {{.*}} to <8 x i16>
+; CHECK-NEXT: or <8 x i16>
+; CHECK-NEXT: select <8 x i1>
+; CHECK: ret <8 x i16>
+
 ; CHECK-ORIGINS: @SelectVector
 ; CHECK-ORIGINS: bitcast <8 x i1> {{.*}} to i8
 ; CHECK-ORIGINS: icmp ne i8