[msan] Fix bad interaction between with-calls mode and chained origin…

… tracking.

Origin history should only be recorded for uninitialized values, because it is
meaningless otherwise. This change moves __msan_chain_origin to the runtime
library side and makes it conditional on the corresponding shadow value.

Previous code was correct, but _very_ inefficient.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211700 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Instrumentation/MemorySanitizer.cpp

@@ -569,7 +569,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
             ConvertedShadow, IRB.getIntNTy(8 * (1 << SizeIndex)));
         IRB.CreateCall3(Fn, ConvertedShadow2,
                         IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
-                        updateOrigin(Origin, IRB));
+                        Origin);
       } else {
         Value *Cmp = IRB.CreateICmpNE(
             ConvertedShadow, getCleanShadow(ConvertedShadow), "_mscmp");

test/Instrumentation/MemorySanitizer/instrumentation-with-call-threshold.ll

@@ -1,7 +1,10 @@
 ; Test -msan-instrumentation-with-call-threshold
+; Test that in with-calls mode there are no calls to __msan_chain_origin - they
+; are done from __msan_maybe_store_origin_*.
 
 ; RUN: opt < %s -msan -msan-check-access-address=0 -msan-instrumentation-with-call-threshold=0 -S | FileCheck %s
 ; RUN: opt < %s -msan -msan-check-access-address=0 -msan-instrumentation-with-call-threshold=0 -msan-track-origins=1 -S | FileCheck -check-prefix=CHECK -check-prefix=CHECK-ORIGINS %s
+; RUN: opt < %s -msan -msan-check-access-address=0 -msan-instrumentation-with-call-threshold=0 -msan-track-origins=2 -S | FileCheck -check-prefix=CHECK -check-prefix=CHECK-ORIGINS %s
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
@@ -41,7 +44,10 @@ entry:
 ; CHECK: load {{.*}} @__msan_param_tls
 ; CHECK-ORIGINS: load {{.*}} @__msan_param_origin_tls
 ; CHECK: store
+; CHECK-ORIGINS-NOT: __msan_chain_origin
 ; CHECK-ORIGINS: bitcast i64* {{.*}} to i8*
+; CHECK-ORIGINS-NOT: __msan_chain_origin
 ; CHECK-ORIGINS: call void @__msan_maybe_store_origin_8(
+; CHECK-ORIGINS-NOT: __msan_chain_origin
 ; CHECK: store i64
 ; CHECK: ret void