svolume: Mark channel parameter as earlyclobber

For all our MMX/SSE code, we use a temporary channel variable, assigned
to the DI register, which is zero'ed as the very first operation in the
inline assembly code, before any other code is run.

With GCC 9.1, while using -O2, the DI register is also used for the
input operand. This is perfectly legal, but causes our code to become
incorrect because the output operand that is assigned to DI is not
explicitly marked as being clobbered before inputs are read.

This change fixes the problem by adding an earlyclobber annotation (&)
to the DI output argument.

diff --git a/src/pulsecore/svolume_mmx.c b/src/pulsecore/svolume_mmx.c
index 5d39234..c5848cc 100644 (file)
--- a/src/pulsecore/svolume_mmx.c
+++ b/src/pulsecore/svolume_mmx.c
@@ -149,7 +149,7 @@ static void pa_volume_s16ne_mmx(int16_t *samples, const int32_t *volumes, unsign
         "6:                             \n\t"
         " emms                          \n\t"
 
-        : "+r" (samples), "+r" (volumes), "+r" (length), "=D" (channel), "=&r" (temp)
+        : "+r" (samples), "+r" (volumes), "+r" (length), "=&D" (channel), "=&r" (temp)
 #if defined (__i386__)
         : "m" (channels)
 #else
@@ -228,7 +228,7 @@ static void pa_volume_s16re_mmx(int16_t *samples, const int32_t *volumes, unsign
         "6:                             \n\t"
         " emms                          \n\t"
 
-        : "+r" (samples), "+r" (volumes), "+r" (length), "=D" (channel), "=&r" (temp)
+        : "+r" (samples), "+r" (volumes), "+r" (length), "=&D" (channel), "=&r" (temp)
 #if defined (__i386__)
         : "m" (channels)
 #else

diff --git a/src/pulsecore/svolume_sse.c b/src/pulsecore/svolume_sse.c
index f6d6382..222ff18 100644 (file)
--- a/src/pulsecore/svolume_sse.c
+++ b/src/pulsecore/svolume_sse.c
@@ -147,7 +147,7 @@ static void pa_volume_s16ne_sse2(int16_t *samples, const int32_t *volumes, unsig
         " jne 7b                        \n\t"
         "8:                             \n\t"
 
-        : "+r" (samples), "+r" (volumes), "+r" (length), "=D" (channel), "=&r" (temp)
+        : "+r" (samples), "+r" (volumes), "+r" (length), "=&D" (channel), "=&r" (temp)
 #if defined (__i386__)
         : "m" (channels)
 #else
@@ -239,7 +239,7 @@ static void pa_volume_s16re_sse2(int16_t *samples, const int32_t *volumes, unsig
         " jne 7b                        \n\t"
         "8:                             \n\t"
 
-        : "+r" (samples), "+r" (volumes), "+r" (length), "=D" (channel), "=&r" (temp)
+        : "+r" (samples), "+r" (volumes), "+r" (length), "=&D" (channel), "=&r" (temp)
 #if defined (__i386__)
         : "m" (channels)
 #else