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Pull in r226664 from upstream llvm trunk (by Tim Northover):
AArch64: add backend option to reserve x18 (platform register)
AAPCS64 says that it's up to the platform to specify whether x18 is
reserved, and a first step on that way is to add a flag controlling
it.
From: Andrew Turner <andrew@fubar.geek.nz>
Introduced here: http://svnweb.freebsd.org/changeset/base/277774
Index: lib/Target/AArch64/AArch64RegisterInfo.cpp
===================================================================
--- lib/Target/AArch64/AArch64RegisterInfo.cpp
+++ lib/Target/AArch64/AArch64RegisterInfo.cpp
@@ -33,6 +33,10 @@ using namespace llvm;
#define GET_REGINFO_TARGET_DESC
#include "AArch64GenRegisterInfo.inc"
+static cl::opt<bool>
+ReserveX18("aarch64-reserve-x18", cl::Hidden,
+ cl::desc("Reserve X18, making it unavailable as GPR"));
+
AArch64RegisterInfo::AArch64RegisterInfo(const AArch64InstrInfo *tii,
const AArch64Subtarget *sti)
: AArch64GenRegisterInfo(AArch64::LR), TII(tii), STI(sti) {}
@@ -90,7 +94,7 @@ AArch64RegisterInfo::getReservedRegs(const Machine
Reserved.set(AArch64::W29);
}
- if (STI->isTargetDarwin()) {
+ if (STI->isTargetDarwin() || ReserveX18) {
Reserved.set(AArch64::X18); // Platform register
Reserved.set(AArch64::W18);
}
@@ -117,7 +121,7 @@ bool AArch64RegisterInfo::isReservedReg(const Mach
return true;
case AArch64::X18:
case AArch64::W18:
- return STI->isTargetDarwin();
+ return STI->isTargetDarwin() || ReserveX18;
case AArch64::FP:
case AArch64::W29:
return TFI->hasFP(MF) || STI->isTargetDarwin();
@@ -379,7 +383,7 @@ unsigned AArch64RegisterInfo::getRegPressureLimit(
case AArch64::GPR64commonRegClassID:
return 32 - 1 // XZR/SP
- (TFI->hasFP(MF) || STI->isTargetDarwin()) // FP
- - STI->isTargetDarwin() // X18 reserved as platform register
+ - (STI->isTargetDarwin() || ReserveX18) // X18 reserved as platform register
- hasBasePointer(MF); // X19
case AArch64::FPR8RegClassID:
case AArch64::FPR16RegClassID:
Index: test/CodeGen/AArch64/arm64-platform-reg.ll
===================================================================
--- test/CodeGen/AArch64/arm64-platform-reg.ll
+++ test/CodeGen/AArch64/arm64-platform-reg.ll
@@ -1,4 +1,5 @@
-; RUN: llc -mtriple=arm64-apple-ios -o - %s | FileCheck %s --check-prefix=CHECK-DARWIN
+; RUN: llc -mtriple=arm64-apple-ios -o - %s | FileCheck %s --check-prefix=CHECK-RESERVE-X18
+; RUN: llc -mtriple=arm64-freebsd-gnu -aarch64-reserve-x18 -o - %s | FileCheck %s --check-prefix=CHECK-RESERVE-X18
; RUN: llc -mtriple=arm64-linux-gnu -o - %s | FileCheck %s
; x18 is reserved as a platform register on Darwin but not on other
@@ -16,11 +17,11 @@ define void @keep_live() {
; CHECK: ldr x18
; CHECK: str x18
-; CHECK-DARWIN-NOT: ldr fp
-; CHECK-DARWIN-NOT: ldr x18
-; CHECK-DARWIN: Spill
-; CHECK-DARWIN-NOT: ldr fp
-; CHECK-DARWIN-NOT: ldr x18
-; CHECK-DARWIN: ret
+; CHECK-RESERVE-X18-NOT: ldr fp
+; CHECK-RESERVE-X18-NOT: ldr x18
+; CHECK-RESERVE-X18: Spill
+; CHECK-RESERVE-X18-NOT: ldr fp
+; CHECK-RESERVE-X18-NOT: ldr x18
+; CHECK-RESERVE-X18: ret
ret void
}
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