[llvm] 0e55d4f - [AA] Refine ModRefInfo for llvm.memcpy.* in presence of operand bundles

[Evgeniy Brevnov via llvm-commits]

Author: Evgeniy Brevnov
Date: 2022-01-25T10:15:23+07:00
New Revision: 0e55d4fab0183b6dca82ce127b78ded3db918c27

URL: https://github.com/llvm/llvm-project/commit/0e55d4fab0183b6dca82ce127b78ded3db918c27
DIFF: https://github.com/llvm/llvm-project/commit/0e55d4fab0183b6dca82ce127b78ded3db918c27.diff

LOG: [AA] Refine ModRefInfo for llvm.memcpy.* in presence of operand bundles

Presence of operand bundles changes semantics in respect to ModRef. In particular, spec says: "From the compilers perspective, deoptimization operand bundles make the call sites theyre attached to at least readonly. They read through all of their pointer typed operands (even if theyre not otherwise escaped) and the entire visible heap. Deoptimization operand bundles do not capture their operands except during deoptimization, in which case control will not be returned to the compiled frame". Fix handling of llvm.memcpy.* according to the spec.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D118033

Added: 
    

Modified: 
    llvm/lib/Analysis/BasicAliasAnalysis.cpp
    llvm/test/Analysis/BasicAA/deoptimize.ll

Removed: 
    


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diff  --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index fa9ccb095a21d..b4c9859628379 100644
--- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -1020,9 +1020,9 @@ ModRefInfo BasicAAResult::getModRefInfo(const CallBase *Call,
         getBestAAResults().alias(MemoryLocation::getForDest(Inst), Loc, AAQI);
     // It's also possible for Loc to alias both src and dest, or neither.
     ModRefInfo rv = ModRefInfo::NoModRef;
-    if (SrcAA != AliasResult::NoAlias)
+    if (SrcAA != AliasResult::NoAlias || Call->hasReadingOperandBundles())
       rv = setRef(rv);
-    if (DestAA != AliasResult::NoAlias)
+    if (DestAA != AliasResult::NoAlias || Call->hasClobberingOperandBundles())
       rv = setMod(rv);
     return rv;
   }

diff  --git a/llvm/test/Analysis/BasicAA/deoptimize.ll b/llvm/test/Analysis/BasicAA/deoptimize.ll
index 89297e2583186..18a41bd5405ae 100644
--- a/llvm/test/Analysis/BasicAA/deoptimize.ll
+++ b/llvm/test/Analysis/BasicAA/deoptimize.ll
@@ -22,7 +22,7 @@ define i32 @test_memcpy_with_deopt() {
 ; CHECK-LABEL: Function: test_memcpy_with_deopt:
 ; CHECK: Just Mod:  Ptr: i8* %A	<->  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %A, i8* %B, i64 -1, i1 false) [ "deopt"() ]
 ; CHECK: Just Ref:  Ptr: i8* %B	<->  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %A, i8* %B, i64 -1, i1 false) [ "deopt"() ]
-; CHECK: NoModRef:  Ptr: i32* @G1	<->  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %A, i8* %B, i64 -1, i1 false) [ "deopt"() ]
+; CHECK: Just Ref:  Ptr: i32* @G1	<->  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %A, i8* %B, i64 -1, i1 false) [ "deopt"() ]
 
   %A = alloca i8
   %B = alloca i8