mirrors/stb
1
0
Fork 0
mirror of https://github.com/nothings/stb synced 2024-12-15 12:22:55 +03:00
Code Issues Packages Projects Releases Wiki Activity

stb_image: NEON and SSE2 SIMD detection fixes.

Browse Source 
This fixes two things. First, the logic to disable SSE2 on
GCC unless "-msse2" was not specific enough, and ended up
disabling SIMD support on NEON targets entirely. Shuffle
the detection logic around to make that bit x86-specific.

Second, 32-bit MinGW assumes 16-byte aligned stacks, but this is
not in the Windows ABI and hence DLLs and callbacks don't
necessarily provide it. This caused a crash.

This can be fixed by providing the right command-line option,
which we have no control over. As a compromise, disable the SSE2
path on MinGW unless a specific #define explained in the comments
is set. That way, we default to safe (never-crashing) behavior
unless the user explicitly signals they know what they're doing.
This commit is contained in:
Fabian Giesen 2015-02-17 01:21:40 -08:00
parent bdef693b7c
commit 4b0c6f6634
1 changed files with 20 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
stb_image.h
View File

@ -624,7 +624,12 @@ typedef unsigned char validate_uint32[sizeof(stbi__uint32)==4 ? 1 : -1];
#define STBI_FREE(p) free(p)
#endif
#if defined(__GNUC__) && !defined(__SSE2__) && !defined(STBI_NO_SIMD)
// x86/x64 detection
#if defined(__x86_64__) || defined(_M_X64) || defined(__i386) || defined(_M_IX86)
#define STBI_X86_TARGET
#endif
#if defined(__GNUC__) && defined(STBI_X86_TARGET) && !defined(__SSE2__) && !defined(STBI_NO_SIMD)
// gcc doesn't support sse2 intrinsics unless you compile with -msse2,
// (but compiling with -msse2 allows the compiler to use SSE2 everywhere;
// this is just broken and gcc are jerks for not fixing it properly
@ -632,7 +637,20 @@ typedef unsigned char validate_uint32[sizeof(stbi__uint32)==4 ? 1 : -1];
#define STBI_NO_SIMD
#endif
#if !defined(STBI_NO_SIMD) && (defined(__x86_64__) || defined(_M_X64) || defined(__i386) || defined(_M_IX86))
#if defined(__MINGW32__) && defined(STBI_X86_TARGET) && !defined(STBI_MINGW_ENABLE_SSE2) && !defined(STBI_NO_SIMD)
// 32-bit MinGW wants ESP to be 16-byte aligned, but this is not in the
// Windows ABI and VC++ as well as Windows DLLs don't maintain that invariant.
// As a result, enabling SSE2 on 32-bit MinGW is dangerous when not
// simultaneously enabling "-mstackrealign".
//
// See https://github.com/nothings/stb/issues/81 for more information.
//
// So default to no SSE2 on 32-bit MinGW. If you've read this far and added
// -mstackrealign to your build settings, feel free to #define STBI_MINGW_ENABLE_SSE2.
#define STBI_NO_SIMD
#endif
#if !defined(STBI_NO_SIMD) && defined(STBI_X86_TARGET)
#define STBI_SSE2
#include <emmintrin.h>