[clang] 5fba4c4 - [AArch64] Don't #define __ARM_FP when there's no FPU.

[Simon Tatham via cfe-commits]

Author: Simon Tatham
Date: 2023-03-13T16:43:25Z
New Revision: 5fba4c4d08bdb38d0df2fd43afa4bec4f3809b66

URL: https://github.com/llvm/llvm-project/commit/5fba4c4d08bdb38d0df2fd43afa4bec4f3809b66
DIFF: https://github.com/llvm/llvm-project/commit/5fba4c4d08bdb38d0df2fd43afa4bec4f3809b66.diff

LOG: [AArch64] Don't #define __ARM_FP when there's no FPU.

On some R-profile CPUs, leaving out the FPU is an option. Clang will
accept `-march=armv8-r+nofp`, but it's currently not possible to find
out via the preprocessor whether it's in that mode (e.g. to change or
disable inline asm statements in your code).

The __ARM_FP macro, which has a bit set for each size of floating
point number supported by the hardware, is the natural thing to test.
But Clang was defining it unconditionally on AArch64. Now it checks
for FP support before defining it at all.

Reviewed By: tmatheson, DavidSpickett

Differential Revision: https://reviews.llvm.org/D145781

Added: 
    

Modified: 
    clang/lib/Basic/Targets/AArch64.cpp
    clang/lib/Basic/Targets/AArch64.h
    clang/test/Preprocessor/aarch64-target-features.c

Removed: 
    


################################################################################
diff  --git a/clang/lib/Basic/Targets/AArch64.cpp b/clang/lib/Basic/Targets/AArch64.cpp
index 7f331004348f1..b274dd2672268 100644
--- a/clang/lib/Basic/Targets/AArch64.cpp
+++ b/clang/lib/Basic/Targets/AArch64.cpp
@@ -373,7 +373,8 @@ void AArch64TargetInfo::getTargetDefines(const LangOptions &Opts,
   Builder.defineMacro("__ARM_ALIGN_MAX_STACK_PWR", "4");
 
   // 0xe implies support for half, single and double precision operations.
-  Builder.defineMacro("__ARM_FP", "0xE");
+  if (FPU & FPUMode)
+    Builder.defineMacro("__ARM_FP", "0xE");
 
   // PCS specifies this for SysV variants, which is all we support. Other ABIs
   // may choose __ARM_FP16_FORMAT_ALTERNATIVE.
@@ -709,6 +710,8 @@ void AArch64TargetInfo::setFeatureEnabled(llvm::StringMap<bool> &Features,
 bool AArch64TargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
                                              DiagnosticsEngine &Diags) {
   for (const auto &Feature : Features) {
+    if (Feature == "-fp-armv8")
+      HasNoFP = true;
     if (Feature == "-neon")
       HasNoNeon = true;
     if (Feature == "-sve")
@@ -937,6 +940,11 @@ bool AArch64TargetInfo::handleTargetFeatures(std::vector<std::string> &Features,
   setDataLayout();
   setArchFeatures();
 
+  if (HasNoFP) {
+    FPU &= ~FPUMode;
+    FPU &= ~NeonMode;
+    FPU &= ~SveMode;
+  }
   if (HasNoNeon) {
     FPU &= ~NeonMode;
     FPU &= ~SveMode;

diff  --git a/clang/lib/Basic/Targets/AArch64.h b/clang/lib/Basic/Targets/AArch64.h
index ee2c179d7c3df..f6e12176a77ec 100644
--- a/clang/lib/Basic/Targets/AArch64.h
+++ b/clang/lib/Basic/Targets/AArch64.h
@@ -26,7 +26,11 @@ class LLVM_LIBRARY_VISIBILITY AArch64TargetInfo : public TargetInfo {
   static const TargetInfo::GCCRegAlias GCCRegAliases[];
   static const char *const GCCRegNames[];
 
-  enum FPUModeEnum { FPUMode, NeonMode = (1 << 0), SveMode = (1 << 1) };
+  enum FPUModeEnum {
+    FPUMode = (1 << 0),
+    NeonMode = (1 << 1),
+    SveMode = (1 << 2),
+  };
 
   unsigned FPU = FPUMode;
   bool HasCRC = false;
@@ -73,6 +77,7 @@ class LLVM_LIBRARY_VISIBILITY AArch64TargetInfo : public TargetInfo {
   bool HasWFxT = false;
   bool HasJSCVT = false;
   bool HasFCMA = false;
+  bool HasNoFP = false;
   bool HasNoNeon = false;
   bool HasNoSVE = false;
   bool HasFMV = true;

diff  --git a/clang/test/Preprocessor/aarch64-target-features.c b/clang/test/Preprocessor/aarch64-target-features.c
index 2a2f7efe34130..09f464466a56c 100644
--- a/clang/test/Preprocessor/aarch64-target-features.c
+++ b/clang/test/Preprocessor/aarch64-target-features.c
@@ -341,6 +341,10 @@
 // CHECK-MARCH-2: "-cc1"{{.*}} "-triple" "aarch64{{.*}}" "-target-feature" "-fp-armv8" "-target-feature" "-neon" "-target-feature" "-crc" "-target-feature" "-crypto"
 // CHECK-MARCH-3: "-cc1"{{.*}} "-triple" "aarch64{{.*}}" "-target-feature" "-neon"
 
+// While we're checking +nofp, also make sure it stops defining __ARM_FP
+// RUN: %clang -target aarch64-none-linux-gnu -march=armv8-r+nofp -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-NOFP %s
+// CHECK-NOFP-NOT: #define __ARM_FP{{ }}
+
 // Check +sm4:
 //
 // RUN: %clang -target aarch64 -march=armv8.2a+sm4 -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-SM4 %s