[llvm] [clang] [llvm][ARM] Emit MVE .arch_extension after .fpu directive if it does not include MVE features (PR #71545)

[via llvm-commits]

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@@ -0,0 +1,56 @@
+; REQUIRES: arm-registered-target
+; RUN: %clang --target=arm-none-eabi -mcpu=cortex-m85 -mfloat-abi=hard -save-temps=obj -S -o - %s | FileCheck %s
+; RUN: %clang --target=arm-none-eabi -mcpu=cortex-m55 -mfloat-abi=hard -save-temps=obj -S -o - %s | FileCheck %s
+; RUN: %clang --target=arm-none-eabi -mcpu=cortex-m85 -mfloat-abi=hard -O2 -c -mthumb -save-temps=obj %s
+; RUN: %clang --target=arm-none-eabi -mcpu=cortex-m55 -mfloat-abi=hard -O2 -c -mthumb -save-temps=obj %s
+; CHECK: .fpu   fpv5-d16
+; CHECK  .arch_extension mve.fp
+target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+target triple = "thumbv8.1m.main-none-unknown-eabihf"
+
+%struct.dummy_t = type { float, float, float, float }
+
+define dso_local signext i8 @foo(ptr noundef %handle) #0 {
+entry:
+  %handle.addr = alloca ptr, align 4
+  store ptr %handle, ptr %handle.addr, align 4
+  %0 = load ptr, ptr %handle.addr, align 4
+  %a = getelementptr inbounds %struct.dummy_t, ptr %0, i32 0, i32 0
+  %1 = load float, ptr %a, align 4
+  %sub = fsub float 0x3F5439DE40000000, %1
+  %2 = load ptr, ptr %handle.addr, align 4
+  %a1 = getelementptr inbounds %struct.dummy_t, ptr %2, i32 0, i32 0
+  %3 = load float, ptr %a1, align 4
+  %4 = call float @llvm.fmuladd.f32(float 0x3F847AE140000000, float %sub, float %3)
+  store float %4, ptr %a1, align 4
+  %5 = load ptr, ptr %handle.addr, align 4
+  %b = getelementptr inbounds %struct.dummy_t, ptr %5, i32 0, i32 1
+  %6 = load float, ptr %b, align 4
+  %sub2 = fsub float 0x3F5439DE40000000, %6
+  %7 = load ptr, ptr %handle.addr, align 4
+  %b3 = getelementptr inbounds %struct.dummy_t, ptr %7, i32 0, i32 1
+  %8 = load float, ptr %b3, align 4
+  %9 = call float @llvm.fmuladd.f32(float 0x3F947AE140000000, float %sub2, float %8)
+  store float %9, ptr %b3, align 4
+  %10 = load ptr, ptr %handle.addr, align 4
+  %c = getelementptr inbounds %struct.dummy_t, ptr %10, i32 0, i32 2
+  %11 = load float, ptr %c, align 4
+  %sub4 = fsub float 0x3F5439DE40000000, %11
+  %12 = load ptr, ptr %handle.addr, align 4
+  %c5 = getelementptr inbounds %struct.dummy_t, ptr %12, i32 0, i32 2
+  %13 = load float, ptr %c5, align 4
+  %14 = call float @llvm.fmuladd.f32(float 0x3F9EB851E0000000, float %sub4, float %13)
+  store float %14, ptr %c5, align 4
+  %15 = load ptr, ptr %handle.addr, align 4
+  %d = getelementptr inbounds %struct.dummy_t, ptr %15, i32 0, i32 3
+  %16 = load float, ptr %d, align 4
+  %sub6 = fsub float 0x3F5439DE40000000, %16
+  %17 = load ptr, ptr %handle.addr, align 4
+  %d7 = getelementptr inbounds %struct.dummy_t, ptr %17, i32 0, i32 3
+  %18 = load float, ptr %d7, align 4
+  %19 = call float @llvm.fmuladd.f32(float 0x3FA47AE140000000, float %sub6, float %18)
+  store float %19, ptr %d7, align 4
+  ret i8 0
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simpal01 wrote:

i not only want to check if the directives are emitted but also want to check if the MVE floating point instructions can be compiled.

https://github.com/llvm/llvm-project/pull/71545