[x86] AVX FP compare builtins should require AVX target feature (PR28112)

[spatel]

Summary

This is a fix for PR28112:
https://llvm.org/bugs/show_bug.cgi?id=28112

The FP comparison intrinsics that take an immediate parameter rather than specifying a comparison predicate in the function name were added with AVX (these are macros in avxintrin.h). This makes clang behave more like like gcc and matches the Intel documentation, eg:
VCMPPS: m128 _mm_cmp_ps(m128 a, __m128 b, const int imm)

'V' means this is intended to only work with the AVX form of the instruction.

[echristo]

The 128 bit versions should only be selecting for sse functions and shouldn't need avx to work? What instructions are getting emitted here?

[spatel]

In D21306#456965, @echristo wrote:

The 128 bit versions should only be selecting for sse functions and shouldn't need avx to work? What instructions are getting emitted here?

No, the 128-bit versions of these C intrinsics are strictly for AVX versions of the instructions (eg, vcmpps).

Example from the bug report:

cmp = _mm_cmp_ps((__m128)a, (__m128)b, 8);

We're currently emitting illegal SSE instructions like:

cmpps	$0x8, %xmm1, %xmm0  <--- anything over '7' is reserved/undef

[RKSimon]

It seems like part of the need for this is because the _mm_cmp_ps style intrinsics are defined as macros (to get around the problem of trying to use an immediate as an argument):

#define _mm_cmp_ps(a, b, c) __extension__ ({ \
  (__m128)__builtin_ia32_cmpps((__v4sf)(__m128)(a), \
                               (__v4sf)(__m128)(b), (c)); })

which means clang can't use a target("avx") attribute to stop their use.

Given that I'm happy with this patch's approach - anyone else have any suggestions?

[RKSimon]

LGTM - the compile warning is clear and it could be a problem if we allow undefined values through on pre-AVX targets.

The only other thing we could do is handle these in CGBuiltin and 'accept' 0-7 values through on sse/sse2 targets and assert on other values but I don't see how this would be better.

include/clang/Basic/BuiltinsX86.def

 TARGET_BUILTIN(__builtin_ia32_comisdneq, "iV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_ucomisdeq, "iV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_ucomisdlt, "iV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_ucomisdle, "iV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_ucomisdgt, "iV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_ucomisdge, "iV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_ucomisdneq, "iV2dV2d", "", "sse2")
 
-TARGET_BUILTIN(__builtin_ia32_cmpps, "V4fV4fV4fIc", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpeqps, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpltps, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpleps, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpunordps, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpneqps, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpnltps, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpnleps, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpordps, "V4fV4fV4f", "", "sse")
-TARGET_BUILTIN(__builtin_ia32_cmpss, "V4fV4fV4fIc", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpeqss, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpltss, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpless, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpunordss, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpneqss, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpnltss, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpnless, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_cmpordss, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_minps, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_maxps, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_minss, "V4fV4fV4f", "", "sse")
 TARGET_BUILTIN(__builtin_ia32_maxss, "V4fV4fV4f", "", "sse")
 
-TARGET_BUILTIN(__builtin_ia32_cmppd, "V2dV2dV2dIc", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmpeqpd, "V2dV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmpltpd, "V2dV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmplepd, "V2dV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmpunordpd, "V2dV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmpneqpd, "V2dV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmpnltpd, "V2dV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmpnlepd, "V2dV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmpordpd, "V2dV2dV2d", "", "sse2")
-TARGET_BUILTIN(__builtin_ia32_cmpsd, "V2dV2dV2dIc", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmpeqsd, "V2dV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmpltsd, "V2dV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmplesd, "V2dV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmpunordsd, "V2dV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmpneqsd, "V2dV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmpnltsd, "V2dV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmpnlesd, "V2dV2dV2d", "", "sse2")
 TARGET_BUILTIN(__builtin_ia32_cmpordsd, "V2dV2dV2d", "", "sse2")

 TARGET_BUILTIN(__builtin_ia32_minps256, "V8fV8fV8f", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_vpermilvarpd, "V2dV2dV2LLi", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_vpermilvarps, "V4fV4fV4i", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_vpermilvarpd256, "V4dV4dV4LLi", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_vpermilvarps256, "V8fV8fV8i", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_blendvpd256, "V4dV4dV4dV4d", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_blendvps256, "V8fV8fV8fV8f", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_dpps256, "V8fV8fV8fIc", "", "avx")
+TARGET_BUILTIN(__builtin_ia32_cmppd, "V2dV2dV2dIc", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_cmppd256, "V4dV4dV4dIc", "", "avx")
+TARGET_BUILTIN(__builtin_ia32_cmpps, "V4fV4fV4fIc", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_cmpps256, "V8fV8fV8fIc", "", "avx")
+TARGET_BUILTIN(__builtin_ia32_cmpsd, "V2dV2dV2dIc", "", "avx")
+TARGET_BUILTIN(__builtin_ia32_cmpss, "V4fV4fV4fIc", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_cvtdq2ps256, "V8fV8i", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_cvtpd2ps256, "V4fV4d", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_cvtps2dq256, "V8iV8f", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_cvtpd2dq256, "V4iV4d", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_vperm2f128_pd256, "V4dV4dV4dIc", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_vperm2f128_ps256, "V8fV8fV8fIc", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_vperm2f128_si256, "V8iV8iV8iIc", "", "avx")
 TARGET_BUILTIN(__builtin_ia32_sqrtpd256, "V4dV4d", "", "avx")

test/CodeGen/target-features-error-2.c

-// RUN: %clang_cc1 %s -triple=x86_64-linux-gnu -S -verify -o -
+// RUN: %clang_cc1 %s -triple=x86_64-linux-gnu -S -verify -o - -D NEED_SSE42
+// RUN: %clang_cc1 %s -triple=x86_64-linux-gnu -S -verify -o - -D NEED_AVX_1
+// RUN: %clang_cc1 %s -triple=x86_64-linux-gnu -S -verify -o - -D NEED_AVX_2
+// RUN: %clang_cc1 %s -triple=x86_64-linux-gnu -S -verify -o - -D NEED_AVX_3
+// RUN: %clang_cc1 %s -triple=x86_64-linux-gnu -S -verify -o - -D NEED_AVX_4
+
 #define __MM_MALLOC_H
 #include <x86intrin.h>
 
+#if NEED_SSE42
 int baz(__m256i a) {
   return _mm256_extract_epi32(a, 3); // expected-error {{always_inline function '_mm256_extract_epi32' requires target feature 'sse4.2', but would be inlined into function 'baz' that is compiled without support for 'sse4.2'}}
 }
+#endif
+
+#if NEED_AVX_1
+__m128 need_avx(__m128 a, __m128 b) {
+  return _mm_cmp_ps(a, b, 0); // expected-error {{'__builtin_ia32_cmpps' needs target feature avx}}
+}
+#endif
+
+#if NEED_AVX_2
+__m128 need_avx(__m128 a, __m128 b) {
+  return _mm_cmp_ss(a, b, 0); // expected-error {{'__builtin_ia32_cmpss' needs target feature avx}}
+}
+#endif
+
+#if NEED_AVX_3
+__m128d need_avx(__m128d a, __m128d b) {
+  return _mm_cmp_pd(a, b, 0); // expected-error {{'__builtin_ia32_cmppd' needs target feature avx}}
+}
+#endif
+
+#if NEED_AVX_4
+__m128d need_avx(__m128d a, __m128d b) {
+  return _mm_cmp_sd(a, b, 0); // expected-error {{'__builtin_ia32_cmpsd' needs target feature avx}}
+}
+#endif