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[FuncSpec] Allow ConstExprs that are function pointers
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Authored by SjoerdMeijer on Oct 11 2021, 10:58 AM.

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ChuanqiXu
snehasish

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rGfc0fa85171e6: [FuncSpec] Allow ConstExprs that are function pointers

Summary

This is a follow up of D110529 that disallowed constexprs. That change introduced a regression as this also disallowed constexprs that are function pointers, which which is actually one of the motivating examples we do want to support.

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Repository: rG LLVM Github Monorepo

Event Timeline

SjoerdMeijer created this revision.Oct 11 2021, 10:58 AM

Herald added subscribers: ormris, hiraditya. · View Herald TranscriptOct 11 2021, 10:58 AM

SjoerdMeijer requested review of this revision.Oct 11 2021, 10:58 AM

Herald added a project: Restricted Project. · View Herald TranscriptOct 11 2021, 10:58 AM

Harbormaster completed remote builds in B128160: Diff 378736.Oct 11 2021, 10:58 AM

lgtm

This revision is now accepted and ready to land.Oct 11 2021, 3:36 PM

LGTM.

Thanks for the speedy reviews!

This revision was landed with ongoing or failed builds.Oct 12 2021, 3:45 AM

Closed by commit rGfc0fa85171e6: [FuncSpec] Allow ConstExprs that are function pointers (authored by SjoerdMeijer). · Explain Why

This revision was automatically updated to reflect the committed changes.

SjoerdMeijer added a commit: rGfc0fa85171e6: [FuncSpec] Allow ConstExprs that are function pointers.

Revision Contents

Path

Size

llvm/

lib/

Transforms/

IPO/

FunctionSpecialization.cpp

8 lines

test/

Transforms/

FunctionSpecialization/

function-specialization-constant-expression3.ll

29 lines

Diff 378955

llvm/lib/Transforms/IPO/FunctionSpecialization.cpp

Show First 20 Lines • Show All 671 Lines • ▼ Show 20 Lines	for (User *U : F->users()) {
// If the parent of the call site will never be executed, we don't need		// If the parent of the call site will never be executed, we don't need
// to worry about the passed value.		// to worry about the passed value.
if (!Solver.isBlockExecutable(CS.getParent()))		if (!Solver.isBlockExecutable(CS.getParent()))
continue;		continue;

auto *V = CS.getArgOperand(A->getArgNo());		auto *V = CS.getArgOperand(A->getArgNo());
if (isa<PoisonValue>(V))		if (isa<PoisonValue>(V))
return false;		return false;
if (isa<ConstantExpr>(V))
		// For now, constant expressions are fine but only if they are function
		// calls.
		if (auto *CE = dyn_cast<ConstantExpr>(V))
		if (!isa<Function>(CE->getOperand(0)))
return false;		return false;

// TrackValueOfGlobalVariable only tracks scalar global variables.		// TrackValueOfGlobalVariable only tracks scalar global variables.
if (auto *GV = dyn_cast<GlobalVariable>(V)) {		if (auto *GV = dyn_cast<GlobalVariable>(V)) {
// Check if we want to specialize on the address of non-constant		// Check if we want to specialize on the address of non-constant
// global values.		// global values.
if (!GV->isConstant())		if (!GV->isConstant())
if (!SpecializeOnAddresses)		if (!SpecializeOnAddresses)
return false;		return false;
▲ Show 20 Lines • Show All 155 Lines • Show Last 20 Lines

llvm/test/Transforms/FunctionSpecialization/function-specialization-constant-expression3.ll

This file was added.

				; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
				; RUN: opt -function-specialization -force-function-specialization -S < %s \| FileCheck %s

				define i32 @main() {
				; CHECK-LABEL: @main(
				; CHECK-NEXT: bb:
				; CHECK-NEXT: tail call void @wombat.1(i8* undef, i64 undef, i64 undef, i32 (i8, i8)* bitcast (i32 ()* @quux to i32 (i8, i8)*))
				; CHECK-NEXT: tail call void @wombat.2(i8* undef, i64 undef, i64 undef, i32 (i8, i8)* bitcast (i32 ()* @eggs to i32 (i8, i8)*))
				; CHECK-NEXT: ret i32 undef
				;
				bb:
				tail call void @wombat(i8* undef, i64 undef, i64 undef, i32 (i8, i8)* bitcast (i32 ()* @quux to i32 (i8, i8)*))
				tail call void @wombat(i8* undef, i64 undef, i64 undef, i32 (i8, i8)* bitcast (i32 ()* @eggs to i32 (i8, i8)*))
				ret i32 undef
				}

				declare i32 @quux()
				declare i32 @eggs()

				define internal void @wombat(i8* %arg, i64 %arg1, i64 %arg2, i32 (i8, i8)* %arg3) {
				; CHECK-LABEL: @wombat(
				; CHECK-NEXT: bb4:
				; CHECK-NEXT: [[TMP:%.]] = tail call i32 [[ARG3:%.]](i8* undef, i8* undef)
				; CHECK-NEXT: ret void
				;
				bb4:
				%tmp = tail call i32 %arg3(i8* undef, i8* undef)
				ret void
				}