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[Analysis] Attribute Range should not prevent tail call optimization #91122

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May 8, 2024
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7 changes: 4 additions & 3 deletions llvm/lib/CodeGen/Analysis.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -593,9 +593,10 @@ bool llvm::attributesPermitTailCall(const Function *F, const Instruction *I,

// Following attributes are completely benign as far as calling convention
// goes, they shouldn't affect whether the call is a tail call.
for (const auto &Attr : {Attribute::Alignment, Attribute::Dereferenceable,
Attribute::DereferenceableOrNull, Attribute::NoAlias,
Attribute::NonNull, Attribute::NoUndef}) {
for (const auto &Attr :
{Attribute::Alignment, Attribute::Dereferenceable,
Attribute::DereferenceableOrNull, Attribute::NoAlias,
Attribute::NonNull, Attribute::NoUndef, Attribute::Range}) {
CallerAttrs.removeAttribute(Attr);
CalleeAttrs.removeAttribute(Attr);
}
Expand Down
7 changes: 4 additions & 3 deletions llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -62,9 +62,10 @@ bool TargetLowering::isInTailCallPosition(SelectionDAG &DAG, SDNode *Node,
// the return. Ignore following attributes because they don't affect the
// call sequence.
AttrBuilder CallerAttrs(F.getContext(), F.getAttributes().getRetAttrs());
for (const auto &Attr : {Attribute::Alignment, Attribute::Dereferenceable,
Attribute::DereferenceableOrNull, Attribute::NoAlias,
Attribute::NonNull, Attribute::NoUndef})
for (const auto &Attr :
{Attribute::Alignment, Attribute::Dereferenceable,
Attribute::DereferenceableOrNull, Attribute::NoAlias,
Attribute::NonNull, Attribute::NoUndef, Attribute::Range})
CallerAttrs.removeAttribute(Attr);

if (CallerAttrs.hasAttributes())
Expand Down
53 changes: 53 additions & 0 deletions llvm/test/CodeGen/X86/tailcall-range.ll
Original file line number Diff line number Diff line change
@@ -0,0 +1,53 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 4
; RUN: llc -mtriple=x86_64-linux < %s | FileCheck %s

define range(i32 0, 2) i32 @foo(ptr %this) {
; CHECK-LABEL: foo:
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: movzbl (%rdi), %eax
; CHECK-NEXT: retq
entry:
%call = load volatile i1, ptr %this, align 1
%spec.select = zext i1 %call to i32
ret i32 %spec.select
}

define range(i32 0, 2) i32 @bar(ptr %this) {
; CHECK-LABEL: bar:
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: xorl %edi, %edi
; CHECK-NEXT: jmp foo@PLT # TAILCALL
entry:
%ret = musttail call i32 @foo(ptr null)
ret i32 %ret
}

declare i64 @llvm.llround.f32(float) nounwind readnone
define range(i64 0, 8) i64 @testmsxs(float %x) {
; CHECK-LABEL: testmsxs:
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: jmp llroundf@PLT # TAILCALL
entry:
%ret = tail call i64 @llvm.llround.f32(float %x)
ret i64 %ret
}

declare i32 @callee()

define range(i32 0, 2) i32 @func_with_range_attr() {
; CHECK-LABEL: func_with_range_attr:
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: jmp callee@PLT # TAILCALL
entry:
%ret = musttail call i32 @callee()
ret i32 %ret
}

define i32 @call_with_range_attr() {
; CHECK-LABEL: call_with_range_attr:
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: jmp callee@PLT # TAILCALL
entry:
%ret = musttail call range(i32 0, 2) i32 @callee()
ret i32 %ret
}