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[Analysis] Attribute deref/deref_or_null should not prevent tail call optimization

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This commit is contained in:
Dávid Bolvanský
2019-11-06 23:07:17 +01:00
parent 77a60f0df6
commit 62ad212825
2 changed files with 41 additions and 1 deletions
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6
llvm/lib/CodeGen/Analysis.cpp
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@@ -567,12 +567,16 @@ bool llvm::attributesPermitTailCall(const Function *F, const Instruction *I,
AttrBuilder CalleeAttrs(cast<CallInst>(I)->getAttributes(),
AttributeList::ReturnIndex);
// NoAlias and NonNull are completely benign as far as calling convention
// Following attributes are completely benign as far as calling convention
// goes, they shouldn't affect whether the call is a tail call.
CallerAttrs.removeAttribute(Attribute::NoAlias);
CalleeAttrs.removeAttribute(Attribute::NoAlias);
CallerAttrs.removeAttribute(Attribute::NonNull);
CalleeAttrs.removeAttribute(Attribute::NonNull);
CallerAttrs.removeAttribute(Attribute::Dereferenceable);
CalleeAttrs.removeAttribute(Attribute::Dereferenceable);
CallerAttrs.removeAttribute(Attribute::DereferenceableOrNull);
CalleeAttrs.removeAttribute(Attribute::DereferenceableOrNull);
if (CallerAttrs.contains(Attribute::ZExt)) {
if (!CalleeAttrs.contains(Attribute::ZExt))

36
llvm/test/CodeGen/X86/tail-call-deref.ll Normal file
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@@ -0,0 +1,36 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -mtriple=x86_64-linux < %s | FileCheck %s
declare i8* @foo()
define dereferenceable(8) i8* @test1() nounwind {
; CHECK-LABEL: test1:
; CHECK: # %bb.0:
; CHECK-NEXT: jmp foo # TAILCALL
%ret = tail call i8* @foo()
ret i8* %ret
}
define i8* @test2() nounwind {
; CHECK-LABEL: test2:
; CHECK: # %bb.0:
; CHECK-NEXT: jmp foo # TAILCALL
%ret = tail call dereferenceable(8) i8* @foo()
ret i8* %ret
}
define dereferenceable_or_null(8) i8* @test3() nounwind {
; CHECK-LABEL: test3:
; CHECK: # %bb.0:
; CHECK-NEXT: jmp foo # TAILCALL
%ret = tail call i8* @foo()
ret i8* %ret
}
define i8* @test4() nounwind {
; CHECK-LABEL: test4:
; CHECK: # %bb.0:
; CHECK-NEXT: jmp foo # TAILCALL
%ret = tail call dereferenceable_or_null(8) i8* @foo()
ret i8* %ret
}