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[AMDGPU] Re-enable closed-world assumption as an opt-in feature #115371

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merged 1 commit into from
Dec 10, 2024
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[AMDGPU] Re-enable closed-world assumption as an opt-in feature #115371

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4 changes: 4 additions & 0 deletions llvm/lib/Target/AMDGPU/AMDGPUAttributor.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1286,6 +1286,10 @@ static bool runImpl(Module &M, AnalysisGetter &AG, TargetMachine &TM,

Attributor A(Functions, InfoCache, AC);

LLVM_DEBUG(dbgs() << "[AMDGPUAttributor] Module " << M.getName() << " is "
<< (AC.IsClosedWorldModule ? "" : "not ")
<< "assumed to be a closed world.\n");

for (auto *F : Functions) {
A.getOrCreateAAFor<AAAMDAttributes>(IRPosition::function(*F));
A.getOrCreateAAFor<AAUniformWorkGroupSize>(IRPosition::function(*F));
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13 changes: 11 additions & 2 deletions llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp
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Expand Up @@ -454,6 +454,11 @@ static cl::opt<bool> NewRegBankSelect(
"regbankselect"),
cl::init(false), cl::Hidden);

static cl::opt<bool> HasClosedWorldAssumption(
"amdgpu-link-time-closed-world",
cl::desc("Whether has closed-world assumption at link time"),
cl::init(false), cl::Hidden);

extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeAMDGPUTarget() {
// Register the target
RegisterTargetMachine<R600TargetMachine> X(getTheR600Target());
Expand Down Expand Up @@ -859,8 +864,12 @@ void AMDGPUTargetMachine::registerPassBuilderCallbacks(PassBuilder &PB) {
PM.addPass(InternalizePass(mustPreserveGV));
PM.addPass(GlobalDCEPass());
}
if (EnableAMDGPUAttributor)
PM.addPass(AMDGPUAttributorPass(*this));
if (EnableAMDGPUAttributor) {
AMDGPUAttributorOptions Opt;
if (HasClosedWorldAssumption)
Opt.IsClosedWorld = true;
PM.addPass(AMDGPUAttributorPass(*this, Opt));
}
}
});

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12 changes: 12 additions & 0 deletions llvm/test/LTO/AMDGPU/closed-world-assumption.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
; RUN: opt -S -mtriple=amdgcn-amd-amdhsa -O3 -debug-only=amdgpu-attributor -o - %s 2>&1 | FileCheck %s --check-prefix=NO-CW
; RUN: opt -S -mtriple=amdgcn-amd-amdhsa -passes="lto<O3>" -debug-only=amdgpu-attributor -o - %s 2>&1 | FileCheck %s --check-prefix=NO-CW
; RUN: opt -S -mtriple=amdgcn-amd-amdhsa -passes="lto<O3>" -debug-only=amdgpu-attributor -amdgpu-link-time-closed-world=1 -o - %s 2>&1 | FileCheck %s --check-prefix=CW

; REQUIRES: amdgpu-registered-target
; REQUIRES: asserts

; NO-CW: Module {{.*}} is not assumed to be a closed world.
; CW: Module {{.*}} is assumed to be a closed world.
define hidden noundef i32 @_Z3foov() {
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Does this not have any testable effects? I would expect to see a test that shows the before and after of the expected changes.

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NO-CW and CW, isn't it the difference?

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@jhuber6 jhuber6 Dec 10, 2024 •
edited
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Yeah but that's just a debug message, I would expect to see IR changes. Also there's no sense in using C++ mangling in IR tests.

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that is tested in other files. this PR is just to toggle the switch on/off. it doesn't introduce this as a new feature.

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It's still better to check an actual change, and avoid dependent on asserts builds

ret i32 1
}
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