ref: e535e894196387b12d9fcbc271a98b21572a630b
parent: 7b6cede819a673cc21e896283668b2d3ddd9e623
author: Timothy B. Terriberry <[email protected]>
date: Sat Jul 2 08:14:06 EDT 2022
Work around UBSan unaligned access errors. The underlying objects are all 8-bit integers. Verified that the generated assembly still just uses MOVD. Signed-off-by: Jean-Marc Valin <[email protected]>
--- a/celt/x86/x86cpu.h
+++ b/celt/x86/x86cpu.h
@@ -56,8 +56,16 @@
int opus_select_arch(void);
# endif
+/*MOVD should not impose any alignment restrictions, but the C standard does,
+ and UBSan will report errors if we actually make unaligned accesses.
+ Use this to work around those restrictions (which should hopefully all get
+ optimized to a single MOVD instruction).*/
+#define OP_LOADU_EPI32(x) \
+ (int)((*(unsigned char *)(x) | *((unsigned char *)(x) + 1) << 8U |\
+ *((unsigned char *)(x) + 2) << 16U | (opus_uint32)*((unsigned char *)(x) + 3) << 24U))
+
#define OP_CVTEPI8_EPI32_M32(x) \
- (_mm_cvtepi8_epi32(_mm_cvtsi32_si128(*(int *)(x))))
+ (_mm_cvtepi8_epi32(_mm_cvtsi32_si128(OP_LOADU_EPI32(x))))
#define OP_CVTEPI16_EPI32_M64(x) \
(_mm_cvtepi16_epi32(_mm_loadl_epi64((__m128i *)(x))))