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Differential D118033

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

Authored by ebrevnov on Jan 24 2022, 4:11 AM.

Details

Reviewers
reames
fhahn
nikic
Commits
rG0e55d4fab018: [AA] Refine ModRefInfo for llvm.memcpy.* in presence of operand bundles
Summary

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.

Diff Detail

Event Timeline

ebrevnov created this revision.Jan 24 2022, 4:11 AM
Herald added subscribers: jeroen.dobbelaere, hiraditya. · View Herald TranscriptJan 24 2022, 4:11 AM
ebrevnov requested review of this revision.Jan 24 2022, 4:11 AM
Herald added a project: Restricted Project. · View Herald TranscriptJan 24 2022, 4:11 AM
Herald added a subscriber: llvm-commits. · View Herald Transcript
ebrevnov added a parent revision: D118031: [NFC] New test case for BasicAA and memcy/memmove with deopt.Jan 24 2022, 4:12 AM
Harbormaster completed remote builds in B145206: Diff 402473.Jan 24 2022, 4:12 AM
ebrevnov added reviewers: reames, fhahn, nikic.Jan 24 2022, 4:12 AM
ebrevnov added a child revision: D117095: [BasicAA] Add support for memmove intrinsic.Jan 24 2022, 4:15 AM
ebrevnov mentioned this in D117095: [BasicAA] Add support for memmove intrinsic.Jan 24 2022, 4:39 AM
nikic accepted this revision.Jan 24 2022, 5:39 AM

LGTM

This revision is now accepted and ready to land.Jan 24 2022, 5:39 AM
reames added a comment.Jan 24 2022, 5:11 PM

LGTM as well.

This revision was landed with ongoing or failed builds.Jan 24 2022, 7:15 PM
Closed by commit rG0e55d4fab018: [AA] Refine ModRefInfo for llvm.memcpy.* in presence of operand bundles (authored by Evgeniy Brevnov <ybrevnov@azul.com>). · Explain Why
This revision was automatically updated to reflect the committed changes.
Evgeniy Brevnov <ybrevnov@azul.com> added a commit: rG0e55d4fab018: [AA] Refine ModRefInfo for llvm.memcpy.* in presence of operand bundles.

Revision Contents

PathSize
llvm/
lib/
Analysis/
4 lines
test/
Analysis/
BasicAA/
2 lines

Diff 402473

llvm/lib/Analysis/BasicAliasAnalysis.cpp

Show First 20 Lines • Show All 1,014 Lines • ▼ Show 20 LinesModRefInfo BasicAAResult::getModRefInfo(const CallBase *Call,
// no-alias or must-alias. // no-alias or must-alias.
if (auto *Inst = dyn_cast<AnyMemCpyInst>(Call)) { if (auto *Inst = dyn_cast<AnyMemCpyInst>(Call)) {
AliasResult SrcAA = AliasResult SrcAA =
getBestAAResults().alias(MemoryLocation::getForSource(Inst), Loc, AAQI); getBestAAResults().alias(MemoryLocation::getForSource(Inst), Loc, AAQI);
AliasResult DestAA = AliasResult DestAA =
getBestAAResults().alias(MemoryLocation::getForDest(Inst), Loc, AAQI); getBestAAResults().alias(MemoryLocation::getForDest(Inst), Loc, AAQI);
// It's also possible for Loc to alias both src and dest, or neither. // It's also possible for Loc to alias both src and dest, or neither.
ModRefInfo rv = ModRefInfo::NoModRef; ModRefInfo rv = ModRefInfo::NoModRef;
if (SrcAA != AliasResult::NoAlias) if (SrcAA != AliasResult::NoAlias || Call->hasReadingOperandBundles())
rv = setRef(rv); rv = setRef(rv);
if (DestAA != AliasResult::NoAlias) if (DestAA != AliasResult::NoAlias || Call->hasClobberingOperandBundles())
rv = setMod(rv); rv = setMod(rv);
return rv; return rv;
} }
// Guard intrinsics are marked as arbitrarily writing so that proper control // Guard intrinsics are marked as arbitrarily writing so that proper control
// dependencies are maintained but they never mods any particular memory // dependencies are maintained but they never mods any particular memory
// location. // location.
// //
▲ Show 20 Lines • Show All 886 Lines • Show Last 20 Lines

llvm/test/Analysis/BasicAA/deoptimize.ll

Show All 16 Lines
} }
; By specification calls with deopt bundles reads through all operands and entire heap. ; By specification calls with deopt bundles reads through all operands and entire heap.
; Check that global G1 is reported as Ref by memcpy/memmove calls. ; Check that global G1 is reported as Ref by memcpy/memmove calls.
define i32 @test_memcpy_with_deopt() { define i32 @test_memcpy_with_deopt() {
; CHECK-LABEL: Function: 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 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: 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 %A = alloca i8
%B = alloca i8 %B = alloca i8
store i32 2, i32* @G1 ;; Not referenced by semantics of memcpy but still may be read due to "deopt" store i32 2, i32* @G1 ;; Not referenced by semantics of memcpy but still may be read due to "deopt"
call void @llvm.memcpy.p0i8.p0i8.i64(i8* %A, i8* %B, i64 -1, i1 false) [ "deopt"() ] call void @llvm.memcpy.p0i8.p0i8.i64(i8* %A, i8* %B, i64 -1, i1 false) [ "deopt"() ]
Show All 20 Lines