sbaranga added inline comments.
================
Comment at: lib/Basic/Targets.cpp:4931
@@ -4931,1 +4930,3 @@
+ if (ArchVersion >= 7 && (CPUProfile != "M" || CPUAttr == "7EM") &&
+ (FPU & VFP4FPU))
Builder.defineMacro("__ARM_FEATURE_FMA", "1");
----------------
rengolin wrote:
> I think just two checks are necessary, here:
>
> (FPU & VFPV4FPU) || (ArchVersion > 7)
>
> and make sure that the right FPU flag is set from the right cores, plus
> "+vfp4".
Yes, that should be sufficient.
================
Comment at: test/CodeGen/arm-neon-fma.c:6
@@ -5,2 +5,3 @@
// RUN: -ffreestanding \
+// RUN: -target-feature +vfp4 \
// RUN: -emit-llvm -o - %s | opt -S -mem2reg | FileCheck %s
----------------
rengolin wrote:
> why not change the cpu to a core that has vfp4?
>
> I know the test is about FMA, not the CPU, but this is a combination that
> will never occur in the wild...
Sure, good point.
================
Comment at: test/Sema/arm_vfma.c:1
@@ -1,2 +1,2 @@
-// RUN: %clang_cc1 -triple thumbv7s-apple-ios7.0 -target-feature +neon
-fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple thumbv7s-apple-ios7.0 -target-feature +neon
-target-feature +vfp4 -fsyntax-only -verify %s
#include <arm_neon.h>
----------------
rengolin wrote:
> It's possible that v7 Apple cores always have FMA? I'd make sure of that
> before forcing the flag here. We don't want to disable it inadvertently.
>
> @t.p.northover, can you confirm Apple's support for VFP4?
If they do support it and don't have the vfp4 feature, then before this patch
clang/llvm wouldn't have emitted a fma/vfma instruction anyway in any
circumstances (because the backend will not generate it). The backend would
instead legalize it with fmaf() libcalls - but that's not the correct behaviour
according to the spec.
http://reviews.llvm.org/D18963
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