[PATCH 5/6 V2] [pcm_dmix assembly] refactor the PIC mode

29 Apr 2020

From: Frédéric Recoules frederic.recoules@orange.fr
Note: newer versions of GCC accept that ebx is declared
      in the clobber list.
Signed-off-by: Frédéric Recoules frederic.recoules@orange.fr
---
 src/pcm/pcm_dmix_i386.h   | 93 ++++++++++++++++++++++++++++++---------
 src/pcm/pcm_dmix_x86_64.h | 59 ++++++++++++++++++++-----
 2 files changed, 120 insertions(+), 32 deletions(-)

diff --git a/src/pcm/pcm_dmix_i386.h b/src/pcm/pcm_dmix_i386.h
index d9bf8f50..b28ae787 100644
--- a/src/pcm/pcm_dmix_i386.h
+++ b/src/pcm/pcm_dmix_i386.h
@@ -26,6 +26,10 @@
  *
  */
+#if defined(__GNUC__) && __GNUC__ < 5 && defined(__PIC__)
+#  define BOUNDED_EBX
+#endif
+
 /*
  *  for plain i386
  */
@@ -34,8 +38,9 @@ static void MIX_AREAS_16(unsigned int size,
    		 volatile signed int *sum, size_t dst_step,
    		 size_t src_step, size_t sum_step)
 {
+#     ifdef BOUNDED_EBX
    unsigned int old_ebx;
-
+#     endif
    /*
     *  ESI - src
     *  EDI - dst
@@ -46,8 +51,9 @@ static void MIX_AREAS_16(unsigned int size,
     */
    __asm__ __volatile__ (
    	"\n"
-
+#            ifdef BOUNDED_EBX
    	"\tmovl %%ebx, %[old_ebx]\n"	/* ebx is GOT pointer (-fPIC) */
+#            endif
    	/*
    	 *  initialization, load ESI, EDI, EBX registers
    	 */
@@ -140,13 +146,20 @@ static void MIX_AREAS_16(unsigned int size,
    	"\tjnz 1b\n"
"7:"
+#            ifdef BOUNDED_EBX
    	"\tmovl %[old_ebx], %%ebx\n"	/* ebx is GOT pointer (-fPIC) */
-
-		: [size] "+m" (size), [old_ebx] "=m" (old_ebx)
+#            endif
+		: [size] "+m" (size)
+#               ifdef BOUNDED_EBX
+		  , [old_ebx] "=m" (old_ebx)
+#               endif
    	: [dst] "m" (dst), [src] "m" (src), [sum] "m" (sum),
    	  [dst_step] "m" (dst_step),  [src_step] "m" (src_step),
    	  [sum_step] "m" (sum_step)
    	: "esi", "edi", "edx", "ecx", "eax", "memory", "cc"
+#               ifndef BOUNDED_EBX
+		  , "ebx"
+#               endif
    );
 }
@@ -158,8 +171,9 @@ static void MIX_AREAS_16_MMX(unsigned int size,
    		     volatile signed int *sum, size_t dst_step,
    		     size_t src_step, size_t sum_step)
 {
+#     ifdef BOUNDED_EBX
    unsigned int old_ebx;
-
+#     endif
    /*
     *  ESI - src
     *  EDI - dst
@@ -170,8 +184,9 @@ static void MIX_AREAS_16_MMX(unsigned int size,
     */
    __asm__ __volatile__ (
    	"\n"
-
+#            ifdef BOUNDED_EBX
    	"\tmovl %%ebx, %[old_ebx]\n"	/* ebx is GOT pointer (-fPIC) */
+#            endif
    	/*
    	 *  initialization, load ESI, EDI, EBX registers and clear MM1
    	 */
@@ -231,13 +246,20 @@ static void MIX_AREAS_16_MMX(unsigned int size,
    	"\tjnz 1b\n"
    	"\temms\n"
                 "5:"
+#            ifdef BOUNDED_EBX
    	"\tmovl %[old_ebx], %%ebx\n"	/* ebx is GOT pointer (-fPIC) */
-
-	        : [size] "+m" (size), [old_ebx] "=m" (old_ebx)
+#            endif
+		: [size] "+m" (size)
+#               ifdef BOUNDED_EBX
+		  , [old_ebx] "=m" (old_ebx)
+#               endif
    	: [dst] "m" (dst), [src] "m" (src), [sum] "m" (sum),
    	  [dst_step] "m" (dst_step),  [src_step] "m" (src_step),
    	  [sum_step] "m" (sum_step)
    	: "esi", "edi", "edx", "ecx", "eax", "memory", "cc"
+#               ifndef BOUNDED_EBX
+		  , "ebx"
+#               endif
 #               ifdef HAVE_MMX
    	  , "mm0", "mm1"
 #               else
@@ -255,8 +277,9 @@ static void MIX_AREAS_32(unsigned int size,
    		 volatile signed int *sum, size_t dst_step,
    		 size_t src_step, size_t sum_step)
 {
+#     ifdef BOUNDED_EBX
    unsigned int old_ebx;
-
+#     endif
    /*
     *  ESI - src
     *  EDI - dst
@@ -267,8 +290,9 @@ static void MIX_AREAS_32(unsigned int size,
     */
    __asm__ __volatile__ (
    	"\n"
-
+#            ifdef BOUNDED_EBX
    	"\tmovl %%ebx, %[old_ebx]\n"	/* ebx is GOT pointer (-fPIC) */
+#            endif
    	/*
    	 *  initialization, load ESI, EDI, EBX registers
    	 */
@@ -350,13 +374,20 @@ static void MIX_AREAS_32(unsigned int size,
    	"\tjmp 1b\n"
"6:"
+#            ifdef BOUNDED_EBX
    	"\tmovl %[old_ebx], %%ebx\n"	/* ebx is GOT pointer (-fPIC) */
-
-		: [size] "+m" (size), [old_ebx] "=m" (old_ebx)
+#            endif
+		: [size] "+m" (size)
+#               ifdef BOUNDED_EBX
+		  , [old_ebx] "=m" (old_ebx)
+#               endif
    	: [dst] "m" (dst), [src] "m" (src), [sum] "m" (sum),
    	  [dst_step] "m" (dst_step),  [src_step] "m" (src_step),
    	  [sum_step] "m" (sum_step)
    	: "esi", "edi", "edx", "ecx", "eax", "memory", "cc"
+#               ifndef BOUNDED_EBX
+		  , "ebx"
+#               endif
    );
 }
@@ -368,8 +399,9 @@ static void MIX_AREAS_24(unsigned int size,
    		 volatile signed int *sum, size_t dst_step,
    		 size_t src_step, size_t sum_step)
 {
+#     ifdef BOUNDED_EBX
    unsigned int old_ebx;
-
+#     endif
    /*
     *  ESI - src
     *  EDI - dst
@@ -380,8 +412,9 @@ static void MIX_AREAS_24(unsigned int size,
     */
    __asm__ __volatile__ (
    	"\n"
-
+#            ifdef BOUNDED_EBX
    	"\tmovl %%ebx, %[old_ebx]\n"	/* ebx is GOT pointer (-fPIC) */
+#            endif
    	/*
    	 *  initialization, load ESI, EDI, EBX registers
    	 */
@@ -456,13 +489,20 @@ static void MIX_AREAS_24(unsigned int size,
    	"\tjmp 1b\n"
"6:"
+#            ifdef BOUNDED_EBX
    	"\tmovl %[old_ebx], %%ebx\n"	/* ebx is GOT pointer (-fPIC) */
-
-	        : [size] "+m" (size), [old_ebx] "=m" (old_ebx)
+#            endif
+		: [size] "+m" (size)
+#               ifdef BOUNDED_EBX
+		  , [old_ebx] "=m" (old_ebx)
+#               endif
    	: [dst] "m" (dst), [src] "m" (src), [sum] "m" (sum),
    	  [dst_step] "m" (dst_step),  [src_step] "m" (src_step),
    	  [sum_step] "m" (sum_step)
    	: "esi", "edi", "edx", "ecx", "eax", "memory", "cc"
+#               ifndef BOUNDED_EBX
+		  , "ebx"
+#               endif
    );
 }
@@ -474,8 +514,9 @@ static void MIX_AREAS_24_CMOV(unsigned int size,
    		      volatile signed int *sum, size_t dst_step,
    		      size_t src_step, size_t sum_step)
 {
+#     ifdef BOUNDED_EBX
    unsigned int old_ebx;
-
+#     endif
    /*
     *  ESI - src
     *  EDI - dst
@@ -486,8 +527,9 @@ static void MIX_AREAS_24_CMOV(unsigned int size,
     */
    __asm__ __volatile__ (
    	"\n"
-
+#            ifdef BOUNDED_EBX
    	"\tmovl %%ebx, %[old_ebx]\n"	/* ebx is GOT pointer (-fPIC) */
+#            endif
    	/*
    	 *  initialization, load ESI, EDI, EBX registers
    	 */
@@ -555,12 +597,23 @@ static void MIX_AREAS_24_CMOV(unsigned int size,
    	"\tjnz 1b\n"
"6:"
+#            ifdef BOUNDED_EBX
    	"\tmovl %[old_ebx], %%ebx\n"	/* ebx is GOT pointer (-fPIC) */
-
-	        : [size] "+m" (size), [old_ebx] "=m" (old_ebx)
+#            endif
+		: [size] "+m" (size)
+#               ifdef BOUNDED_EBX
+		  , [old_ebx] "=m" (old_ebx)
+#               endif
    	: [dst] "m" (dst), [src] "m" (src), [sum] "m" (sum),
    	  [dst_step] "m" (dst_step),  [src_step] "m" (src_step),
    	  [sum_step] "m" (sum_step)
    	: "esi", "edi", "edx", "ecx", "eax", "memory", "cc"
+#               ifndef BOUNDED_EBX
+		  , "ebx"
+#               endif
    );
 }
+
+#ifdef BOUNDED_EBX
+#  undef BOUNDED_EBX
+#endif
diff --git a/src/pcm/pcm_dmix_x86_64.h b/src/pcm/pcm_dmix_x86_64.h
index 8ad1b2a0..f543a134 100644
--- a/src/pcm/pcm_dmix_x86_64.h
+++ b/src/pcm/pcm_dmix_x86_64.h
@@ -27,6 +27,10 @@
  *
  */
+#if defined(__GNUC__) && __GNUC__ < 5 && defined(__PIC__)
+#  define BOUNDED_RBX
+#endif
+
 /*
  *  MMX optimized
  */
@@ -35,8 +39,9 @@ static void MIX_AREAS_16(unsigned int size,
    		 volatile signed int *sum, size_t dst_step,
    		 size_t src_step, size_t sum_step)
 {
+#     ifdef BOUNDED_RBX
    unsigned long long old_rbx;
-
+#     endif
    /*
     *  RSI - src
     *  RDI - dst
@@ -47,8 +52,9 @@ static void MIX_AREAS_16(unsigned int size,
     */
    __asm__ __volatile__ (
    	"\n"
-
+#            ifdef BOUNDED_RBX
    	"\tmovq %%rbx, %[old_rbx]\n"
+#            endif
    	/*
    	 *  initialization, load RSI, RDI, RBX registers and clear MM1
    	 */
@@ -113,13 +119,20 @@ static void MIX_AREAS_16(unsigned int size,
    	"6:"
"\temms\n"
+#            ifdef BOUNDED_RBX
    	"\tmovq %[old_rbx], %%rbx\n"
-
-		: [size] "+m" (size), [old_rbx] "=m" (old_rbx)
+#            endif
+		: [size] "+m" (size)
+#               ifdef BOUNDED_RBX
+		  , [old_rbx] "=m" (old_rbx)
+#               endif
            : [dst] "m" (dst), [src] "m" (src), [sum] "m" (sum),
    	  [dst_step] "m" (dst_step),  [src_step] "m" (src_step),
    	  [sum_step] "m" (sum_step)
    	: "rsi", "rdi", "edx", "ecx", "eax", "memory", "cc"
+#               ifndef BOUNDED_RBX
+		  , "rbx"
+#               endif
 #               ifdef HAVE_MMX
    	  , "mm0", "mm1"
 #               else
@@ -137,8 +150,9 @@ static void MIX_AREAS_32(unsigned int size,
    		 volatile signed int *sum, size_t dst_step,
    		 size_t src_step, size_t sum_step)
 {
+#     ifdef BOUNDED_RBX
    unsigned long long old_rbx;
-
+#     endif
    /*
     *  RSI - src
     *  RDI - dst
@@ -149,8 +163,9 @@ static void MIX_AREAS_32(unsigned int size,
     */
    __asm__ __volatile__ (
    	"\n"
-
+#            ifdef BOUNDED_RBX
    	"\tmovq %%rbx, %[old_rbx]\n"
+#            endif
    	/*
    	 *  initialization, load RSI, RDI, RBX registers
    	 */
@@ -234,13 +249,20 @@ static void MIX_AREAS_32(unsigned int size,
    	"\tjnz 1b\n"
"6:"
+#            ifdef BOUNDED_RBX
    	"\tmovq %[old_rbx], %%rbx\n"
-
-		: [size] "+m" (size), [old_rbx] "=m" (old_rbx)
+#            endif
+		: [size] "+m" (size)
+#               ifdef BOUNDED_RBX
+		  , [old_rbx] "=m" (old_rbx)
+#               endif
            : [dst] "m" (dst), [src] "m" (src), [sum] "m" (sum),
    	  [dst_step] "m" (dst_step),  [src_step] "m" (src_step),
    	  [sum_step] "m" (sum_step)
    	: "rsi", "rdi", "edx", "ecx", "eax", "memory", "cc"
+#               ifndef BOUNDED_RBX
+		  , "rbx"
+#               endif
    );
 }
@@ -252,8 +274,9 @@ static void MIX_AREAS_24(unsigned int size,
    		 volatile signed int *sum, size_t dst_step,
    		 size_t src_step, size_t sum_step)
 {
+#     ifdef BOUNDED_RBX
    unsigned long long old_rbx;
-
+#     endif
    /*
     *  RSI - src
     *  RDI - dst
@@ -264,8 +287,9 @@ static void MIX_AREAS_24(unsigned int size,
     */
    __asm__ __volatile__ (
    	"\n"
-
+#            ifdef BOUNDED_RBX
    	"\tmovq %%rbx, %[old_rbx]\n"
+#            endif
    	/*
    	 *  initialization, load RSI, RDI, RBX registers
    	 */
@@ -337,12 +361,23 @@ static void MIX_AREAS_24(unsigned int size,
    	"\tjnz 1b\n"
"6:"
+#            ifdef BOUNDED_RBX
    	"\tmovq %[old_rbx], %%rbx\n"
-
-		: [size] "+m" (size), [old_rbx] "=m" (old_rbx)
+#            endif
+		: [size] "+m" (size)
+#               ifdef BOUNDED_RBX
+		  , [old_rbx] "=m" (old_rbx)
+#               endif
            : [dst] "m" (dst), [src] "m" (src), [sum] "m" (sum),
    	  [dst_step] "m" (dst_step),  [src_step] "m" (src_step),
    	  [sum_step] "m" (sum_step)
    	: "rsi", "rdi", "edx", "ecx", "eax", "memory", "cc"
+#               ifndef BOUNDED_RBX
+		  , "rbx"
+#               endif
    );
 }
+
+#ifdef BOUNDED_RBX
+#  undef BOUNDED_RBX
+#endif
--
2.17.1
Note: it has not been tested but I can not figure out it could break
something because the compiler is now aware that ebx is clobbered.
Curiously, it seems it significantly reduces the size of the code.

    

[PATCH 5/6 V2] [pcm_dmix assembly] refactor the PIC mode

frederic.recoules＠univ-grenoble-alpes.fr