[clang] Ensure FPU Features are parsed when targeting `cc1as` (PR #134612)

via cfe-commits cfe-commits at lists.llvm.org
Mon Apr 7 04:11:22 PDT 2025


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-arm

Author: Jack Styles (Stylie777)

<details>
<summary>Changes</summary>

Previously, `cc1as` did not consider the Features that can be included from a target's FPU. This could lead to a situation where assembly files could not compile as cc1as did not know if a feature was supported.

With this change, all the features for the FPU will be passed to `cc1as` as `-target-feature` lines. By making this change, it will enable `+nosimd` to be functional, worked on in #<!-- -->130623, and fix a regression introduced in 8fa0f0efce5fb81eb422e6d7eec74c66dafef4a3 so armv7s-apple0darwin targets can utilise VFPv4 correctly.

Co-authored-by: Martin Storsjö <martin@<!-- -->martin.st>

---
Full diff: https://github.com/llvm/llvm-project/pull/134612.diff


6 Files Affected:

- (modified) clang/docs/ReleaseNotes.rst (+4) 
- (modified) clang/lib/Driver/ToolChains/Arch/ARM.cpp (+7-10) 
- (added) clang/test/Driver/arm-fpu-selection.s (+32) 
- (added) clang/test/Driver/armv7-default-neon.s (+12) 
- (added) clang/test/Driver/armv7s-default-vfpv4.s (+9) 
- (modified) clang/test/Driver/armv8.1m.main.s (+35-16) 


``````````diff
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 5217e04b5e83f..acbb2f435c864 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -38,6 +38,9 @@ Potentially Breaking Changes
 - Fix missing diagnostics for uses of declarations when performing typename access,
   such as when performing member access on a '[[deprecated]]' type alias.
   (#GH58547)
+- For ARM targets, when using cc1as, the features included in the selected CPU or
+  Architecture's FPU are now loaded and utilized. If you wish not to use a specific feature,
+  the relevant ``+no`` option will need to be amended to the command line option.
 
 C/C++ Language Potentially Breaking Changes
 -------------------------------------------
@@ -463,6 +466,7 @@ X86 Support
 
 Arm and AArch64 Support
 ^^^^^^^^^^^^^^^^^^^^^^^
+- For ARM targets, cc1as now considers the FPU's features for the selected CPU or Arch.
 
 Android Support
 ^^^^^^^^^^^^^^^
diff --git a/clang/lib/Driver/ToolChains/Arch/ARM.cpp b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
index e50cb3836f2c9..ff0e52aa285b1 100644
--- a/clang/lib/Driver/ToolChains/Arch/ARM.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
@@ -679,20 +679,17 @@ llvm::ARM::FPUKind arm::getARMTargetFeatures(const Driver &D,
         CPUArgFPUKind != llvm::ARM::FK_INVALID ? CPUArgFPUKind : ArchArgFPUKind;
     (void)llvm::ARM::getFPUFeatures(FPUKind, Features);
   } else {
-    bool Generic = true;
-    if (!ForAS) {
-      std::string CPU = arm::getARMTargetCPU(CPUName, ArchName, Triple);
-      if (CPU != "generic")
-        Generic = false;
-      llvm::ARM::ArchKind ArchKind =
-          arm::getLLVMArchKindForARM(CPU, ArchName, Triple);
-      FPUKind = llvm::ARM::getDefaultFPU(CPU, ArchKind);
-      (void)llvm::ARM::getFPUFeatures(FPUKind, Features);
-    }
+    std::string CPU = arm::getARMTargetCPU(CPUName, ArchName, Triple);
+    bool Generic = CPU == "generic";
     if (Generic && (Triple.isOSWindows() || Triple.isOSDarwin()) &&
         getARMSubArchVersionNumber(Triple) >= 7) {
       FPUKind = llvm::ARM::parseFPU("neon");
       (void)llvm::ARM::getFPUFeatures(FPUKind, Features);
+    } else {
+      llvm::ARM::ArchKind ArchKind =
+          arm::getLLVMArchKindForARM(CPU, ArchName, Triple);
+      FPUKind = llvm::ARM::getDefaultFPU(CPU, ArchKind);
+      (void)llvm::ARM::getFPUFeatures(FPUKind, Features);
     }
   }
 
diff --git a/clang/test/Driver/arm-fpu-selection.s b/clang/test/Driver/arm-fpu-selection.s
new file mode 100644
index 0000000000000..c40e0f5b25852
--- /dev/null
+++ b/clang/test/Driver/arm-fpu-selection.s
@@ -0,0 +1,32 @@
+// REQUIRES: arm-registered-target
+// Ensures that when targeting an ARM target with an Asm file, clang
+// collects the features from the FPU. This is critical in the
+// activation of NEON for supported targets. The Cortex-R52 will be
+// used and tested for VFP and NEON Support
+
+// RUN: %clang -target arm-none-eabi -mcpu=cortex-r52 -c %s -o /dev/null | count 0
+// RUN: %clang -target arm-none-eabi -mcpu=cortex-r52 -c %s -o /dev/null -### 2>&1 | FileCheck --check-prefix=CHECK-TARGET-FEATURES %s
+
+// Check that NEON and VFPV5 have been activated when using Cortex-R52 when using cc1as
+// CHECK-TARGET-FEATURES: "-target-feature" "+vfp2sp"
+// CHECK-TARGET-FEATURES: "-target-feature" "+vfp3"
+// CHECK-TARGET-FEATURES: "-target-feature" "+fp-armv8"
+// CHECK-TARGET-FEATURES: "-target-feature" "+fp-armv8d16"
+// CHECK-TARGET-FEATURES: "-target-feature" "+fp-armv8d16sp"
+// CHECK-TARGET-FEATURES: "-target-feature" "+fp-armv8sp"
+// CHECK-TARGET-FEATURES: "-target-feature" "+neon"
+
+  vadd.f32 s0, s1, s2
+  vadd.f64 d0, d1, d2
+  vcvt.u32.f32 s0, s0, #1
+  vcvt.u32.f64 d0, d0, #1
+  vcvtb.f32.f16 s0, s1
+  vcvtb.f64.f16 d0, s1
+  vfma.f32 s0, s1, s2
+  vfma.f64 d0, d1, d2
+  vcvta.u32.f32 s0, s1
+  vcvta.u32.f64 s0, d1
+  vadd.f32 q0, q1, q2
+  vcvt.f32.f16 q0, d1
+  vfma.f32 q0, q1, q2
+  vcvta.u32.f32 q0, q1
diff --git a/clang/test/Driver/armv7-default-neon.s b/clang/test/Driver/armv7-default-neon.s
new file mode 100644
index 0000000000000..9caef97ce3b46
--- /dev/null
+++ b/clang/test/Driver/armv7-default-neon.s
@@ -0,0 +1,12 @@
+// Ensure that we can assemble NEON by just specifying an armv7
+// Apple or Windows target.
+
+// REQUIRES: arm-registered-target
+// RUN: %clang -c -target armv7-apple-darwin -o /dev/null %s
+// RUN: %clang -c -target armv7-apple-darwin -o /dev/null %s -### 2>&1 | FileCheck --check-prefix=CHECK-TARGET-FEATURES %s
+// RUN: %clang -c -target armv7-windows -o /dev/null %s
+// RUN: %clang -c -target armv7-windows -o /dev/null %s -### 2>&1 | FileCheck --check-prefix=CHECK-TARGET-FEATURES %s
+
+// CHECK-TARGET-FEATURES: "-target-feature" "+neon"
+
+vadd.i32 q0, q0, q0
diff --git a/clang/test/Driver/armv7s-default-vfpv4.s b/clang/test/Driver/armv7s-default-vfpv4.s
new file mode 100644
index 0000000000000..c9c8dbab9ae93
--- /dev/null
+++ b/clang/test/Driver/armv7s-default-vfpv4.s
@@ -0,0 +1,9 @@
+// Ensure that we can assemble VFPv4 by just specifying an armv7s target.
+
+// REQUIRES: arm-registered-target
+// RUN: %clang -c -target armv7s-apple-darwin -o /dev/null %s
+// RUN: %clang -c -target armv7s-apple-darwin -o /dev/null %s -### 2>&1 | FileCheck --check-prefix=CHECK-TARGET-FEATURES %s
+
+// CHECK-TARGET-FEATURES: "-target-feature" "+vfp4"
+
+vfma.f32 q1, q2, q3
diff --git a/clang/test/Driver/armv8.1m.main.s b/clang/test/Driver/armv8.1m.main.s
index 8fc94cf772fae..a660e56c2d1e7 100644
--- a/clang/test/Driver/armv8.1m.main.s
+++ b/clang/test/Driver/armv8.1m.main.s
@@ -8,21 +8,21 @@
 # RUN: not %clang -c -target arm-none-none-eabi -march=armv8.1-m.main+fp -o /dev/null %s 2>%t
 # RUN:      FileCheck --check-prefix=ERROR-V81M_FP < %t %s
 # RUN: not %clang -c -target arm-none-none-eabi -march=armv8.1-m.main+nofp -o /dev/null %s 2>%t
-# RUN:      FileCheck --check-prefix=ERROR-V81M_FP < %t %s
+# RUN:      FileCheck --check-prefix=ERROR-V81M_NOFP < %t %s
 # RUN: not %clang -c -target arm-none-none-eabi -march=armv8.1-m.main+fp.dp -o /dev/null %s 2>%t
 # RUN:      FileCheck --check-prefix=ERROR-V81M_FPDP < %t %s
 # RUN: not %clang -c -target arm-none-none-eabi -march=armv8.1-m.main+nofp.dp -o /dev/null %s 2>%t
-# RUN:      FileCheck --check-prefix=ERROR-V81M_FPDP < %t %s
+# RUN:      FileCheck --check-prefix=ERROR-V81M_NOFPDP < %t %s
 # RUN: not %clang -c -target arm-none-none-eabi -march=armv8.1-m.main+mve -o /dev/null %s 2>%t
 # RUN:      FileCheck --check-prefix=ERROR-V81M_MVE < %t %s
 # RUN: not %clang -c -target arm-none-none-eabi -march=armv8.1-m.main+nomve -o /dev/null %s 2>%t
-# RUN:      FileCheck --check-prefix=ERROR-V81M_MVE < %t %s
+# RUN:      FileCheck --check-prefix=ERROR-V81M_NOMVE < %t %s
 # RUN: not %clang -c -target arm-none-none-eabi -march=armv8.1-m.main+mve+fp -o /dev/null %s 2>%t
 # RUN:      FileCheck --check-prefix=ERROR-V81M_MVE_FP < %t %s
 # RUN: not %clang -c -target arm-none-none-eabi -march=armv8.1-m.main+mve.fp -o /dev/null %s 2>%t
 # RUN:      FileCheck --check-prefix=ERROR-V81M_MVEFP < %t %s
 # RUN: not %clang -c -target arm-none-none-eabi -march=armv8.1-m.main+nomve.fp -o /dev/null %s 2>%t
-# RUN:      FileCheck --check-prefix=ERROR-V81M_MVEFP < %t %s
+# RUN:      FileCheck --check-prefix=ERROR-V81M_NOMVEFP < %t %s
 
 .syntax unified
 .thumb
@@ -35,28 +35,41 @@ qadd     r0, r1, r2
 # ERROR-V8M: :[[@LINE-1]]:1: error
 # ERROR-V81M: :[[@LINE-2]]:1: error
 # ERROR-V81M_FP: :[[@LINE-3]]:1: error
-# ERROR-V81M_FPDP: :[[@LINE-4]]:1: error
+# ERROR-V81M_NOFP: :[[@LINE-4]]:1: error
+# ERROR-V81M_FPDP: :[[@LINE-5]]:1: error
+# ERROR-V81M_NOFPDP: :[[@LINE-6]]:1: error
+# ERROR-V81M_NOMVE: :[[@LINE-7]]:1: error
+# ERROR-V81M_NOMVEFP: :[[@LINE-8]]:1: error
 
 vadd.f16 s0, s1, s2
 # ERROR-V8M: :[[@LINE-1]]:1: error
-# ERROR-V81M: :[[@LINE-2]]:1: error
-# ERROR-V81M_DSP: :[[@LINE-3]]:1: error
-# ERROR-V81M_MVE: :[[@LINE-4]]:1: error
+# ERROR-V81M_NOFP: :[[@LINE-2]]:1: error
 
 vabs.f32 s0, s1
-# ERROR-V8M: :[[@LINE-1]]:1: error
-# ERROR-V81M: :[[@LINE-2]]:1: error
-# ERROR-V81M_DSP: :[[@LINE-3]]:1: error
-# ERROR-V81M_MVE: :[[@LINE-4]]:1: error
+# ERROR-V81M_NOFP: :[[@LINE-1]]:1: error
 
-vcmp.f64 d0,d1
+vabs.s32 q0, q1
 # ERROR-V8M: :[[@LINE-1]]:1: error
 # ERROR-V81M: :[[@LINE-2]]:1: error
 # ERROR-V81M_DSP: :[[@LINE-3]]:1: error
 # ERROR-V81M_FP: :[[@LINE-4]]:1: error
-# ERROR-V81M_MVE: :[[@LINE-5]]:1: error
-# ERROR-V81M_MVE_FP: :[[@LINE-6]]:1: error
-# ERROR-V81M_MVEFP: :[[@LINE-7]]:1: error
+# ERROR-V81M_NOFP: :[[@LINE-5]]:1: error
+# ERROR-V81M_FPDP: :[[@LINE-6]]:1: error
+# ERROR-V81M_NOFPDP: :[[@LINE-7]]:1: error
+# ERROR-V81M_NOMVE: :[[@LINE-8]]:1: error
+# ERROR-V81M_NOMVEFP: :[[@LINE-9]]:1: error
+
+vcmp.f64 d0,d1
+# ERROR-V81M: :[[@LINE-1]]:1: error
+# ERROR-V81M_DSP: :[[@LINE-2]]:1: error
+# ERROR-V81M_FP: :[[@LINE-3]]:1: error
+# ERROR-V81M_NOFP: :[[@LINE-4]]:1: error
+# ERROR-V81M_NOFPDP: :[[@LINE-5]]:1: error
+# ERROR-V81M_MVE: :[[@LINE-6]]:1: error
+# ERROR-V81M_NOMVE: :[[@LINE-7]]:1: error
+# ERROR-V81M_MVE_FP: :[[@LINE-8]]:1: error
+# ERROR-V81M_MVEFP: :[[@LINE-9]]:1: error
+# ERROR-V81M_NOMVEFP: :[[@LINE-10]]:1: error
 
 asrl r0, r1, r2
 # ERROR-V8M: :[[@LINE-1]]:1: error
@@ -64,6 +77,9 @@ asrl r0, r1, r2
 # ERROR-V81M_DSP: :[[@LINE-3]]:1: error
 # ERROR-V81M_FP: :[[@LINE-4]]:1: error
 # ERROR-V81M_FPDP: :[[@LINE-5]]:1: error
+# ERROR-V81M_NOFPDP: :[[@LINE-6]]:1: error
+# ERROR-V81M_NOMVE: :[[@LINE-7]]:1: error
+# ERROR-V81M_NOMVEFP: :[[@LINE-8]]:1: error
 
 vcadd.i8 q0, q1, q2, #90
 # ERROR-V8M: :[[@LINE-1]]:1: error
@@ -71,3 +87,6 @@ vcadd.i8 q0, q1, q2, #90
 # ERROR-V81M_DSP: :[[@LINE-3]]:1: error
 # ERROR-V81M_FP: :[[@LINE-4]]:1: error
 # ERROR-V81M_FPDP: :[[@LINE-5]]:1: error
+# ERROR-V81M_NOFPDP: :[[@LINE-6]]:1: error
+# ERROR-V81M_NOMVE: :[[@LINE-7]]:1: error
+# ERROR-V81M_NOMVEFP: :[[@LINE-8]]:1: error

``````````

</details>


https://github.com/llvm/llvm-project/pull/134612


More information about the cfe-commits mailing list