[Inline] Only consider provenance captures for scoped alias metadata

[nikic]

When determining whether an escape source may alias with a noalias argument, only take provenance captures into account. If only the address of the argument was captured, an access through the escape source is not legal.

[llvmbot]

@llvm/pr-subscribers-llvm-transforms

Author: Nikita Popov (nikic)

Changes

When determining whether an escape source may alias with a noalias argument, only take provenance captures into account. If only the address of the argument was captured, an access through the escape source is not legal.

---

Full diff: https://github.com/llvm/llvm-project/pull/138540.diff

2 Files Affected:

• (modified) llvm/lib/Transforms/Utils/InlineFunction.cpp (+3-1)
• (modified) llvm/test/Transforms/Inline/noalias-escape-source.ll (+2-2)

diff --git a/llvm/lib/Transforms/Utils/InlineFunction.cpp b/llvm/lib/Transforms/Utils/InlineFunction.cpp
index 7a91620af8272..8d9f8ff68ea10 100644
--- a/llvm/lib/Transforms/Utils/InlineFunction.cpp
+++ b/llvm/lib/Transforms/Utils/InlineFunction.cpp
@@ -1313,7 +1313,9 @@ static void AddAliasScopeMetadata(CallBase &CB, ValueToValueMapTy &VMap,
         // nocapture only guarantees that no copies outlive the function, not
         // that the value cannot be locally captured.
         if (!RequiresNoCaptureBefore ||
-            !PointerMayBeCapturedBefore(A, /* ReturnCaptures */ false, I, &DT))
+            !capturesAnything(PointerMayBeCapturedBefore(
+                A, /*ReturnCaptures=*/false, I, &DT, /*IncludeI=*/false,
+                CaptureComponents::Provenance)))
           NoAliases.push_back(NewScopes[A]);
       }
 
diff --git a/llvm/test/Transforms/Inline/noalias-escape-source.ll b/llvm/test/Transforms/Inline/noalias-escape-source.ll
index 78b31da21a375..09835cb75b780 100644
--- a/llvm/test/Transforms/Inline/noalias-escape-source.ll
+++ b/llvm/test/Transforms/Inline/noalias-escape-source.ll
@@ -82,9 +82,9 @@ define void @test_addr_only_capture(ptr %p) {
 ; CHECK-SAME: ptr [[P:%.*]]) {
 ; CHECK-NEXT:    call void @llvm.experimental.noalias.scope.decl(metadata [[META6:![0-9]+]])
 ; CHECK-NEXT:    call void @capture(ptr captures(address) [[P]])
-; CHECK-NEXT:    [[P2_I:%.*]] = call ptr @get_ptr()
+; CHECK-NEXT:    [[P2_I:%.*]] = call ptr @get_ptr(), !noalias [[META6]]
 ; CHECK-NEXT:    [[V_I:%.*]] = load i32, ptr [[P]], align 4, !alias.scope [[META6]]
-; CHECK-NEXT:    store i32 [[V_I]], ptr [[P2_I]], align 4
+; CHECK-NEXT:    store i32 [[V_I]], ptr [[P2_I]], align 4, !noalias [[META6]]
 ; CHECK-NEXT:    ret void
 ;
   call void @callee_addr_only_capture(ptr %p)

[nikic]

Ping

[dtcxzyw]

LGTM.

[fhahn]

LGTM, thanks

[llvm-ci]

LLVM Buildbot has detected a new failure on builder clang-debian-cpp20 running on clang-debian-cpp20 while building llvm at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/108/builds/13347

Here is the relevant piece of the build log for the reference

Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: tools/llvm-exegesis/RISCV/rvv/filter.test' FAILED ********************
Exit Code: 2

Command Output (stderr):
--
/vol/worker/clang-debian-cpp20/clang-debian-cpp20/build/bin/llvm-exegesis -mtriple=riscv64 -mcpu=sifive-x280 -benchmark-phase=assemble-measured-code --mode=inverse_throughput --opcode-name=PseudoVNCLIPU_WX_M1_MASK     --riscv-filter-config='vtype = {VXRM: rod, AVL: VLMAX, SEW: e(8|16), Policy: ta/mu}' --max-configs-per-opcode=1000 --min-instructions=10 | /vol/worker/clang-debian-cpp20/clang-debian-cpp20/build/bin/FileCheck /vol/worker/clang-debian-cpp20/clang-debian-cpp20/llvm-project/llvm/test/tools/llvm-exegesis/RISCV/rvv/filter.test # RUN: at line 1
+ /vol/worker/clang-debian-cpp20/clang-debian-cpp20/build/bin/llvm-exegesis -mtriple=riscv64 -mcpu=sifive-x280 -benchmark-phase=assemble-measured-code --mode=inverse_throughput --opcode-name=PseudoVNCLIPU_WX_M1_MASK '--riscv-filter-config=vtype = {VXRM: rod, AVL: VLMAX, SEW: e(8|16), Policy: ta/mu}' --max-configs-per-opcode=1000 --min-instructions=10
+ /vol/worker/clang-debian-cpp20/clang-debian-cpp20/build/bin/FileCheck /vol/worker/clang-debian-cpp20/clang-debian-cpp20/llvm-project/llvm/test/tools/llvm-exegesis/RISCV/rvv/filter.test
PseudoVNCLIPU_WX_M1_MASK: Failed to produce any snippet via: instruction has tied variables, avoiding Read-After-Write issue, picking random def and use registers not aliasing each other, for uses, one unique register for each position
FileCheck error: '<stdin>' is empty.
FileCheck command line:  /vol/worker/clang-debian-cpp20/clang-debian-cpp20/build/bin/FileCheck /vol/worker/clang-debian-cpp20/clang-debian-cpp20/llvm-project/llvm/test/tools/llvm-exegesis/RISCV/rvv/filter.test

--

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