[clang] [llvm] Revert "[AArch64] Add support for -ffixed-x30" (PR #88019)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-aarch64

Author: Eli Friedman (efriedma-quic)

<details>
<summary>Changes</summary>

This reverts commit e770153865c53c4fd72a68f23acff33c24e42a08.

This wasn't reviewed, and the functionality in question was intentionally rejected the last time it was discussed in https://reviews.llvm.org/D56305 .

---
Full diff: https://github.com/llvm/llvm-project/pull/88019.diff


4 Files Affected:

- (modified) clang/lib/Driver/ToolChains/Arch/AArch64.cpp (-3) 
- (modified) clang/test/Driver/aarch64-fixed-x-register.c (-4) 
- (modified) llvm/lib/Target/AArch64/AArch64.td (+1-1) 
- (modified) llvm/test/CodeGen/AArch64/arm64-platform-reg.ll (+1-6) 


``````````diff
diff --git a/clang/lib/Driver/ToolChains/Arch/AArch64.cpp b/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
index 3e6e29584df3ac..2cd2b35ee51bc6 100644
--- a/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
@@ -402,9 +402,6 @@ void aarch64::getAArch64TargetFeatures(const Driver &D,
   if (Args.hasArg(options::OPT_ffixed_x28))
     Features.push_back("+reserve-x28");
 
-  if (Args.hasArg(options::OPT_ffixed_x30))
-    Features.push_back("+reserve-x30");
-
   if (Args.hasArg(options::OPT_fcall_saved_x8))
     Features.push_back("+call-saved-x8");
 
diff --git a/clang/test/Driver/aarch64-fixed-x-register.c b/clang/test/Driver/aarch64-fixed-x-register.c
index 29024fde412543..7fc3e3e61105df 100644
--- a/clang/test/Driver/aarch64-fixed-x-register.c
+++ b/clang/test/Driver/aarch64-fixed-x-register.c
@@ -94,10 +94,6 @@
 // RUN: FileCheck --check-prefix=CHECK-FIXED-X28 < %t %s
 // CHECK-FIXED-X28: "-target-feature" "+reserve-x28"
 
-// RUN: %clang --target=aarch64-none-gnu -ffixed-x30 -### %s 2> %t
-// RUN: FileCheck --check-prefix=CHECK-FIXED-X30 < %t %s
-// CHECK-FIXED-X30: "-target-feature" "+reserve-x30"
-
 // Test multiple of reserve-x# options together.
 // RUN: %clang --target=aarch64-none-gnu \
 // RUN: -ffixed-x1 \
diff --git a/llvm/lib/Target/AArch64/AArch64.td b/llvm/lib/Target/AArch64/AArch64.td
index 3af427d526f80c..741c97a3dc009b 100644
--- a/llvm/lib/Target/AArch64/AArch64.td
+++ b/llvm/lib/Target/AArch64/AArch64.td
@@ -212,7 +212,7 @@ def FeatureStrictAlign : SubtargetFeature<"strict-align",
                                           "Disallow all unaligned memory "
                                           "access">;
 
-foreach i = {1-7,9-15,18,20-28,30} in
+foreach i = {1-7,9-15,18,20-28} in
     def FeatureReserveX#i : SubtargetFeature<"reserve-x"#i, "ReserveXRegister["#i#"]", "true",
                                              "Reserve X"#i#", making it unavailable "
                                              "as a GPR">;
diff --git a/llvm/test/CodeGen/AArch64/arm64-platform-reg.ll b/llvm/test/CodeGen/AArch64/arm64-platform-reg.ll
index c598306c2de301..3df2ef7aa59fc8 100644
--- a/llvm/test/CodeGen/AArch64/arm64-platform-reg.ll
+++ b/llvm/test/CodeGen/AArch64/arm64-platform-reg.ll
@@ -34,7 +34,6 @@
 ; RUN: llc -mtriple=arm64-linux-gnu -mattr=+reserve-x26 -o - %s | FileCheck %s --check-prefixes=CHECK-RESERVE,CHECK-RESERVE-X26
 ; RUN: llc -mtriple=arm64-linux-gnu -mattr=+reserve-x27 -o - %s | FileCheck %s --check-prefixes=CHECK-RESERVE,CHECK-RESERVE-X27
 ; RUN: llc -mtriple=arm64-linux-gnu -mattr=+reserve-x28 -o - %s | FileCheck %s --check-prefixes=CHECK-RESERVE,CHECK-RESERVE-X28
-; RUN: llc -mtriple=arm64-linux-gnu -mattr=+reserve-x30 -o - %s | FileCheck %s --check-prefixes=CHECK-RESERVE,CHECK-RESERVE-X30
 
 ; Test multiple of reserve-x# options together.
 ; RUN: llc -mtriple=arm64-linux-gnu \
@@ -73,7 +72,6 @@
 ; RUN: -mattr=+reserve-x26 \
 ; RUN: -mattr=+reserve-x27 \
 ; RUN: -mattr=+reserve-x28 \
-; RUN: -mattr=+reserve-x30 \
 ; RUN: -reserve-regs-for-regalloc=X8,X16,X17,X19 \
 ; RUN: -o - %s | FileCheck %s \
 ; RUN: --check-prefix=CHECK-RESERVE \
@@ -104,8 +102,7 @@
 ; RUN: --check-prefix=CHECK-RESERVE-X25 \
 ; RUN: --check-prefix=CHECK-RESERVE-X26 \
 ; RUN: --check-prefix=CHECK-RESERVE-X27 \
-; RUN: --check-prefix=CHECK-RESERVE-X28 \
-; RUN: --check-prefix=CHECK-RESERVE-X30
+; RUN: --check-prefix=CHECK-RESERVE-X28
 
 ; x18 is reserved as a platform register on Darwin but not on other
 ; systems. Create loads of register pressure and make sure this is respected.
@@ -152,7 +149,6 @@ define void @keep_live() {
 ; CHECK-RESERVE-X26-NOT: ldr x26
 ; CHECK-RESERVE-X27-NOT: ldr x27
 ; CHECK-RESERVE-X28-NOT: ldr x28
-; CHECK-RESERVE-X30-NOT: ldr x30
 ; CHECK-RESERVE: Spill
 ; CHECK-RESERVE-NOT: ldr fp
 ; CHECK-RESERVE-X1-NOT: ldr x1,
@@ -182,7 +178,6 @@ define void @keep_live() {
 ; CHECK-RESERVE-X26-NOT: ldr x26
 ; CHECK-RESERVE-X27-NOT: ldr x27
 ; CHECK-RESERVE-X28-NOT: ldr x28
-; CHECK-RESERVE-X30-NOT: ldr x30
 ; CHECK-RESERVE: ret
   ret void
 }

``````````

</details>


https://github.com/llvm/llvm-project/pull/88019