[XS] Change in coreboot[main]: arch/arm64: Use -mno-implicit-float with clang

[Arthur Heymans (Code Review)]

Arthur Heymans has submitted this change. ( https://review.coreboot.org/c/coreboot/+/81658?usp=email )

Change subject: arch/arm64: Use -mno-implicit-float with clang
......................................................................

arch/arm64: Use -mno-implicit-float with clang

This fixes building inline assembly that uses SIMD registers. This is
for instance the case in the vboot library.

Change-Id: I24fa9d9f81430ea3ecd40de4304a10c6e235fece
Signed-off-by: Arthur Heymans 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/81658
Tested-by: build bot (Jenkins) 
Reviewed-by: Julius Werner 
---
M toolchain.mk
M util/xcompile/xcompile
2 files changed, 6 insertions(+), 1 deletion(-)

Approvals:
  Julius Werner: Looks good to me, approved
  build bot (Jenkins): Verified

diff --git a/toolchain.mk b/toolchain.mk
index f985e88..77fb46e 100644
--- a/toolchain.mk
+++ b/toolchain.mk
@@ -60,7 +60,7 @@
 ARCHDIR-ppc64	:= ppc64

CFLAGS_arm	+=
-CFLAGS_arm64	+= -mgeneral-regs-only
+CFLAGS_arm64	+=
 CFLAGS_riscv	+=
 CFLAGS_x86_32	+=
 CFLAGS_x86_64	+= -mcmodel=large -mno-red-zone
diff --git a/util/xcompile/xcompile b/util/xcompile/xcompile
index 13ed48b..3fb0cb7 100755
--- a/util/xcompile/xcompile
+++ b/util/xcompile/xcompile
@@ -256,6 +256,11 @@
    	testld "$GCC" "$FLAGS_GCC" "${GCCPREFIX}ld${LINKER_SUFFIX}" \
    	  "$LDFLAGS --fix-cortex-a53-843419" && \
    	  LDFLAGS_ARM64_A53_ERRATUM_843419+=" --fix-cortex-a53-843419"
+		  # https://bugs.llvm.org/show_bug.cgi?id=30792
+		  # LLVM/clang runs into problems when encountering SIMD registers in assembly
+		  # with -mgeneral-regs-only. -mno-implicit-float achieves the same though.
+		  CFLAGS_GCC="$CFLAGS_GCC -mgeneral-regs-only" &&
+		  CFLAGS_CLANG="$CFLAGS_CLANG -mno-implicit-float"
    	;;
    riscv)
    	testcc "$GCC" "$FLAGS_GCC -march=rv64iadc_zicsr_zifencei" &&