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[AArch64] Allow global register asm("x18") or asm("w18") under -ffixed-x18 

When using -ffixed-x18, the x18 (or w18) register can safely be used
with the "global register variable" GCC extension, but the backend
fails to recognize it.

Patch by Roland McGrath.

Differential Revision: https://reviews.llvm.org/D31793

llvm-svn: 299799
This commit is contained in:
Petr Hosek 2017-04-07 20:41:58 +00:00
parent df82d93562
commit c3a9e6db38
3 changed files with 33 additions and 0 deletions
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5
llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
View File

@ -4510,7 +4510,12 @@ unsigned AArch64TargetLowering::getRegisterByName(const char* RegName, EVT VT,
SelectionDAG &DAG) const {
unsigned Reg = StringSwitch<unsigned>(RegName)
.Case("sp", AArch64::SP)
.Case("x18", AArch64::X18)
.Case("w18", AArch64::W18)
.Default(0);
if ((Reg == AArch64::X18 || Reg == AArch64::W18) &&
!Subtarget->isX18Reserved())
Reg = 0;
if (Reg)
return Reg;
report_fatal_error(Twine("Invalid register name \""

14
llvm/test/CodeGen/AArch64/aarch64-named-reg-w18.ll Normal file
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@ -0,0 +1,14 @@
; RUN: not llc -mtriple=aarch64-fuchsia -o - %s 2>&1 | FileCheck %s --check-prefix=ERROR
; RUN: llc -mtriple=aarch64-fuchsia -mattr=+reserve-x18 -o - %s
define void @set_w18(i32 %x) {
entry:
; FIXME: Include an allocatable-specific error message
; ERROR: Invalid register name "w18".
tail call void @llvm.write_register.i32(metadata !0, i32 %x)
ret void
}
declare void @llvm.write_register.i32(metadata, i32) nounwind
!0 = !{!"w18"}

14
llvm/test/CodeGen/AArch64/aarch64-named-reg-x18.ll Normal file
View File

@ -0,0 +1,14 @@
; RUN: not llc -mtriple=aarch64-fuchsia -o - %s 2>&1 | FileCheck %s --check-prefix=ERROR
; RUN: llc -mtriple=aarch64-fuchsia -mattr=+reserve-x18 -o - %s
define void @set_x18(i64 %x) {
entry:
; FIXME: Include an allocatable-specific error message
; ERROR: Invalid register name "x18".
tail call void @llvm.write_register.i64(metadata !0, i64 %x)
ret void
}
declare void @llvm.write_register.i64(metadata, i64) nounwind
!0 = !{!"x18"}