[clang] [PowerPC] Make "ca" aliased to "xer" (PR #77557)

[Kai Luo via cfe-commits]

https://github.com/bzEq created https://github.com/llvm/llvm-project/pull/77557

`ca` is not accepted in clobber list of inline assembly right now. Make `ca` aliased to `xer`, so it can be accepted in clobber list.

Fixes #77549.

>From e1caee46dc81e59b8eab0379e200ca2a709801c3 Mon Sep 17 00:00:00 2001
From: Kai Luo <lkail at cn.ibm.com>
Date: Wed, 10 Jan 2024 05:29:22 +0000
Subject: [PATCH 1/2] Alias

---
 clang/lib/Basic/Targets/PPC.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/lib/Basic/Targets/PPC.cpp b/clang/lib/Basic/Targets/PPC.cpp
index 045c273f03c7a0..fa86d93b141180 100644
--- a/clang/lib/Basic/Targets/PPC.cpp
+++ b/clang/lib/Basic/Targets/PPC.cpp
@@ -803,7 +803,7 @@ const TargetInfo::GCCRegAlias PPCTargetInfo::GCCRegAliases[] = {
     {{"fr22"}, "f22"}, {{"fr23"}, "f23"},   {{"fr24"}, "f24"},
     {{"fr25"}, "f25"}, {{"fr26"}, "f26"},   {{"fr27"}, "f27"},
     {{"fr28"}, "f28"}, {{"fr29"}, "f29"},   {{"fr30"}, "f30"},
-    {{"fr31"}, "f31"}, {{"cc"}, "cr0"},
+    {{"fr31"}, "f31"}, {{"cc"}, "cr0"},     {{"ca"},   "xer"},
 };
 
 ArrayRef<TargetInfo::GCCRegAlias> PPCTargetInfo::getGCCRegAliases() const {

>From aaee97fb9f7bef5ff4e3f845fa29d45e9c7a83b0 Mon Sep 17 00:00:00 2001
From: Kai Luo <lkail at cn.ibm.com>
Date: Wed, 10 Jan 2024 05:56:27 +0000
Subject: [PATCH 2/2] CA aliasing to XER

---
 clang/lib/Basic/Targets/PPC.cpp         |  3 +++
 clang/test/CodeGen/ppc-register-names.c | 14 ++++++++++++++
 2 files changed, 17 insertions(+)
 create mode 100644 clang/test/CodeGen/ppc-register-names.c

diff --git a/clang/lib/Basic/Targets/PPC.cpp b/clang/lib/Basic/Targets/PPC.cpp
index fa86d93b141180..abf685f8883971 100644
--- a/clang/lib/Basic/Targets/PPC.cpp
+++ b/clang/lib/Basic/Targets/PPC.cpp
@@ -782,6 +782,9 @@ ArrayRef<const char *> PPCTargetInfo::getGCCRegNames() const {
 const TargetInfo::GCCRegAlias PPCTargetInfo::GCCRegAliases[] = {
     // While some of these aliases do map to different registers
     // they still share the same register name.
+    // Strictly speaking, "ca" is a subregister of "xer". However
+    // currently we don't model other bit fields of "xer", so treat
+    // "ca" aliasing to "xer".
     {{"0"}, "r0"},     {{"1", "sp"}, "r1"}, {{"2"}, "r2"},
     {{"3"}, "r3"},     {{"4"}, "r4"},       {{"5"}, "r5"},
     {{"6"}, "r6"},     {{"7"}, "r7"},       {{"8"}, "r8"},
diff --git a/clang/test/CodeGen/ppc-register-names.c b/clang/test/CodeGen/ppc-register-names.c
new file mode 100644
index 00000000000000..209488c2e5f1ae
--- /dev/null
+++ b/clang/test/CodeGen/ppc-register-names.c
@@ -0,0 +1,14 @@
+// REQUIRES: powerpc-registered-target
+// RUN: %clang -target powerpc64le -c %s -mllvm -stop-after=finalize-isel -o - | \
+// RUN:   FileCheck %s
+// RUN: %clang -target powerpc64 -c %s -mllvm -stop-after=finalize-isel -o - | \
+// RUN:   FileCheck %s
+
+void test_function(void) {
+  asm volatile("":::"ca");
+  asm volatile("":::"xer");
+  // CHECK: call void asm sideeffect "", "~{xer}"()
+  // CHECK: call void asm sideeffect "", "~{xer}"()
+  // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $xer
+  // CHECK: INLINEASM &"", {{.*}} implicit-def early-clobber $xer
+}