[PATCH] D50229: [ARM][AArch64] Add feature +fp16fml

Thu Jul 2 09:42:35 PDT 2020

SjoerdMeijer marked an inline comment as done.
SjoerdMeijer added inline comments.

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Comment at: test/Driver/aarch64-cpus.c:518
+// RUN: %clang -target aarch64 -march=armv8.4-a -### -c %s 2>&1 | FileCheck -check-prefix=GENERICV84A-NO-FP16FML %s
+// GENERICV84A-NO-FP16FML-NOT: "-target-feature" "{{[+-]}}fp16fml"
+// GENERICV84A-NO-FP16FML-NOT: "-target-feature" "{{[+-]}}fullfp16"
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fpetrogalli wrote:
> Hi @SjoerdMeijer , I have noticed that this test does something different from what gcc does (well, claims to do, I haven't checked the actual behavior on gcc).
> 
> From the table in [1], it seems that `armv8.4-a` implies `fp16fml`... who got it right? GCC or clang? Or am I missing something?
> 
> Francesco
> 
> 
> [1] https://gcc.gnu.org/onlinedocs/gcc/AArch64-Options.html#AArch64-Options (see the description of `-march=name`)
I think the ARMARM is pretty clear on this. Copied from one of the instruction descriptions enabled by fp16ml:

"In Armv8.2 and Armv8.3, this is an OPTIONAL instruction. From Armv8.4 it is mandatory for all implementations to support it."

So, looks like this needs fixing.

Repository:
  rC Clang

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D50229/new/

https://reviews.llvm.org/D50229