[PATCH] D118033: [AA] Refine ModRefInfo for llvm.memcpy.* in presence of operand bundles

[Evgeniy via Phabricator via llvm-commits]

ebrevnov created this revision.
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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.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D118033

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


Index: llvm/test/Analysis/BasicAA/deoptimize.ll
===================================================================
--- llvm/test/Analysis/BasicAA/deoptimize.ll
+++ llvm/test/Analysis/BasicAA/deoptimize.ll
@@ -22,7 +22,7 @@
 ; 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
Index: llvm/lib/Analysis/BasicAliasAnalysis.cpp
===================================================================
--- llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -1020,9 +1020,9 @@
         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;
   }


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