[llvm] 8cd2244 - AArch64: correct `preserve_most` and `preserve_all` on Windows (#166436)
via llvm-commits
llvm-commits at lists.llvm.org
Tue Nov 4 13:40:46 PST 2025
Author: Saleem Abdulrasool
Date: 2025-11-04T21:40:42Z
New Revision: 8cd22447af239206daabb42fc63e2824a1f7fb6e
URL: https://github.com/llvm/llvm-project/commit/8cd22447af239206daabb42fc63e2824a1f7fb6e
DIFF: https://github.com/llvm/llvm-project/commit/8cd22447af239206daabb42fc63e2824a1f7fb6e.diff
LOG: AArch64: correct `preserve_most` and `preserve_all` on Windows (#166436)
This fixes register information handling for the `preserve_most` and
`preserve_all` calling conventions on Windows ARM64.
The root issue was cascading `if` statements whose behavior depended on
their order. This patch makes the minimal, tactical change needed for
Swift’s two calling conventions, unblocking current work. A broader
refactor to remove the ordering dependency is still desired and will
follow in a subsequent PR.
Added:
Modified:
llvm/lib/Target/AArch64/AArch64CallingConvention.td
llvm/lib/Target/AArch64/AArch64RegisterInfo.cpp
llvm/test/CodeGen/AArch64/preserve_mostcc.ll
Removed:
################################################################################
diff --git a/llvm/lib/Target/AArch64/AArch64CallingConvention.td b/llvm/lib/Target/AArch64/AArch64CallingConvention.td
index 1b5a713bffdc9..34c85d588f9c4 100644
--- a/llvm/lib/Target/AArch64/AArch64CallingConvention.td
+++ b/llvm/lib/Target/AArch64/AArch64CallingConvention.td
@@ -601,6 +601,12 @@ def CSR_Win_AArch64_AAPCS_SwiftError
def CSR_Win_AArch64_AAPCS_SwiftTail
: CalleeSavedRegs<(sub CSR_Win_AArch64_AAPCS, X20, X22)>;
+def CSR_Win_AArch64_RT_MostRegs
+ : CalleeSavedRegs<(add CSR_Win_AArch64_AAPCS, (sequence "X%u", 9, 15))>;
+
+def CSR_Win_AArch64_RT_AllRegs
+ : CalleeSavedRegs<(add CSR_Win_AArch64_RT_MostRegs, (sequence "Q%u", 8, 31))>;
+
// The Control Flow Guard check call uses a custom calling convention that also
// preserves X0-X8 and Q0-Q7.
def CSR_Win_AArch64_CFGuard_Check : CalleeSavedRegs<(add CSR_Win_AArch64_AAPCS,
diff --git a/llvm/lib/Target/AArch64/AArch64RegisterInfo.cpp b/llvm/lib/Target/AArch64/AArch64RegisterInfo.cpp
index 5bfb19d9a7e61..a5048b9c9e61d 100644
--- a/llvm/lib/Target/AArch64/AArch64RegisterInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64RegisterInfo.cpp
@@ -90,6 +90,16 @@ AArch64RegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
if (MF->getSubtarget<AArch64Subtarget>().isTargetDarwin())
return getDarwinCalleeSavedRegs(MF);
+ if (MF->getFunction().getCallingConv() == CallingConv::PreserveMost)
+ return MF->getSubtarget<AArch64Subtarget>().isTargetWindows()
+ ? CSR_Win_AArch64_RT_MostRegs_SaveList
+ : CSR_AArch64_RT_MostRegs_SaveList;
+
+ if (MF->getFunction().getCallingConv() == CallingConv::PreserveAll)
+ return MF->getSubtarget<AArch64Subtarget>().isTargetWindows()
+ ? CSR_Win_AArch64_RT_AllRegs_SaveList
+ : CSR_AArch64_RT_AllRegs_SaveList;
+
if (MF->getFunction().getCallingConv() == CallingConv::CFGuard_Check)
return CSR_Win_AArch64_CFGuard_Check_SaveList;
if (MF->getSubtarget<AArch64Subtarget>().isTargetWindows()) {
@@ -138,10 +148,6 @@ AArch64RegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
return CSR_AArch64_AAPCS_SwiftError_SaveList;
if (MF->getFunction().getCallingConv() == CallingConv::SwiftTail)
return CSR_AArch64_AAPCS_SwiftTail_SaveList;
- if (MF->getFunction().getCallingConv() == CallingConv::PreserveMost)
- return CSR_AArch64_RT_MostRegs_SaveList;
- if (MF->getFunction().getCallingConv() == CallingConv::PreserveAll)
- return CSR_AArch64_RT_AllRegs_SaveList;
if (MF->getFunction().getCallingConv() == CallingConv::Win64)
// This is for OSes other than Windows; Windows is a separate case further
// above.
diff --git a/llvm/test/CodeGen/AArch64/preserve_mostcc.ll b/llvm/test/CodeGen/AArch64/preserve_mostcc.ll
index 7f0968c8eb339..75c8567e2095e 100644
--- a/llvm/test/CodeGen/AArch64/preserve_mostcc.ll
+++ b/llvm/test/CodeGen/AArch64/preserve_mostcc.ll
@@ -1,4 +1,5 @@
-; RUN: llc < %s -mtriple=arm64-apple-ios-8.0.0 | FileCheck %s
+; RUN: llc < %s -mtriple=arm64-apple-ios-8.0.0 | FileCheck -check-prefix CHECK -check-prefix CHECK-DARWIN %s
+; RUN: llc < %s -mtriple=aarch64-unknown-windiws-msvc | FileCheck -check-prefix CHECK -check-prefix CHECK-WIN %s
declare void @standard_cc_func()
declare preserve_mostcc void @preserve_mostcc_func()
@@ -8,18 +9,26 @@ declare preserve_mostcc void @preserve_mostcc_func()
define preserve_mostcc void @preserve_mostcc1() nounwind {
entry:
;CHECK-LABEL: preserve_mostcc1
-;CHECK-NOT: stp
-;CHECK-NOT: str
-;CHECK: str x15
-;CHECK-NEXT: stp x14, x13,
-;CHECK-NEXT: stp x12, x11,
-;CHECK-NEXT: stp x10, x9,
-;CHECK: bl _standard_cc_func
+;CHECK-DARWIN-NOT: stp
+;CHECK-DARWIN-NOT: str
+;CHECK-DARWIN: str x15
+;CHECK-DARWIN-NEXT: stp x14, x13,
+;CHECK-DARWIN-NEXT: stp x12, x11,
+;CHECK-DARWIN-NEXT: stp x10, x9,
+;CHECK-WIN: stp x15, x14
+;CHECK-WIN-NEXT: stp x13, x12,
+;CHECK-WIN-NEXT: stp x11, x10,
+;CHECK-WIN-NEXT: stp x9, x30
+;CHECK: bl {{_?}}standard_cc_func
call void @standard_cc_func()
-;CHECK: ldp x10, x9,
-;CHECK-NEXT: ldp x12, x11,
-;CHECK-NEXT: ldp x14, x13,
-;CHECK-NEXT: ldr x15
+;CHECK-DARWIN: ldp x10, x9,
+;CHECK-DARWIN-NEXT: ldp x12, x11,
+;CHECK-DARWIN-NEXT: ldp x14, x13,
+;CHECK-DARWIN-NEXT: ldr x15
+;CHECK-WIN: ldp x9, x30
+;CHECK-WIN-NEXT: ldp x11, x10,
+;CHECK-WIN-NEXT: ldp x13, x12,
+;CHECK-WIN-NEXT: ldp x15, x14,
ret void
}
@@ -31,9 +40,10 @@ define preserve_mostcc void @preserve_mostcc2() nounwind {
entry:
;CHECK-LABEL: preserve_mostcc2
;CHECK-NOT: x14
-;CHECK: stp x29, x30,
+;CHECK-DARWIN: stp x29, x30,
+;CHECK-WIN: str x30
;CHECK-NOT: x14
-;CHECK: bl _preserve_mostcc_func
+;CHECK: bl {{_?}}preserve_mostcc_func
call preserve_mostcc void @preserve_mostcc_func()
ret void
}
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