i386: Remove unneeded assignments when triggering SSE exceptions

According to "Intel 64 and IA32 Arch SDM, Vol. 3":

"Because SIMD floating-point exceptions are precise and occur immediately,
the situation does not arise where an x87 FPU instruction, a WAIT/FWAIT
instruction, or another SSE/SSE2/SSE3 instruction will catch a pending
unmasked SIMD floating-point exception."

Remove unneeded assignments to volatile memory.

libgcc/ChangeLog:

	* config/i386/sfp-exceptions.c (__sfp_handle_exceptions) [__SSE_MATH__]:
	Remove unneeded assignments to volatile memory.

libatomic/ChangeLog:

	* config/x86/fenv.c (__atomic_feraiseexcept) [__SSE_MATH__]:
	Remove unneeded assignments to volatile memory.

libgfortran/ChangeLog:

	* config/fpu-387.h (local_feraiseexcept) [__SSE_MATH__]:
	Remove unneeded assignments to volatile memory.

diff --git a/libatomic/ChangeLog b/libatomic/ChangeLog
index 5c0aa2db0c8706e42556b033aff9f3b5d39d2ee6..93ba72ae5ef652b7e39816f772a82f0377411e15 100644 (file)
--- a/libatomic/ChangeLog
+++ b/libatomic/ChangeLog
@@ -1,3 +1,8 @@
+2020-04-19  Uroš Bizjak  <ubizjak@gmail.com>
+
+       * config/x86/fenv.c (__atomic_feraiseexcept) [__SSE_MATH__]:
+       Remove unneeded assignments to volatile memory.
+
 2020-03-12  Release Manager
 
        * GCC 9.3.0 released.

diff --git a/libatomic/config/x86/fenv.c b/libatomic/config/x86/fenv.c
index 9b8a3bd93088e912e3bc0d99e9a891b2cfe6f981..b4c7edc249ebfecf6c6f6ed60df1d4970efb04ef 100644 (file)
--- a/libatomic/config/x86/fenv.c
+++ b/libatomic/config/x86/fenv.c
@@ -57,9 +57,7 @@ __atomic_feraiseexcept (int excepts)
     {
       float f = 0.0f;
 #ifdef __SSE_MATH__
-      volatile float r __attribute__ ((unused));
       asm volatile ("%vdivss\t{%0, %d0|%d0, %0}" : "+x" (f));
-      r = f; /* Needed to trigger exception.   */
 #else
       asm volatile ("fdiv\t{%y0, %0|%0, %y0}" : "+t" (f));
       /* No need for fwait, exception is triggered by emitted fstp.  */
@@ -77,9 +75,7 @@ __atomic_feraiseexcept (int excepts)
     {
       float f = 1.0f, g = 0.0f;
 #ifdef __SSE_MATH__
-      volatile float r __attribute__ ((unused));
       asm volatile ("%vdivss\t{%1, %d0|%d0, %1}" : "+x" (f) : "xm" (g));
-      r = f; /* Needed to trigger exception.   */
 #else
       asm volatile ("fdivs\t%1" : "+t" (f) : "m" (g));
       /* No need for fwait, exception is triggered by emitted fstp.  */
@@ -105,9 +101,7 @@ __atomic_feraiseexcept (int excepts)
     {
       float f = 1.0f, g = 3.0f;
 #ifdef __SSE_MATH__
-      volatile float r __attribute__ ((unused));
       asm volatile ("%vdivss\t{%1, %d0|%d0, %1}" : "+x" (f) : "xm" (g));
-      r = f; /* Needed to trigger exception.   */
 #else
       asm volatile ("fdivs\t%1" : "+t" (f) : "m" (g));
       /* No need for fwait, exception is triggered by emitted fstp.  */

diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index 3dbc003ecbd4954e8e041f3fe884cea236f6f625..9a9d19814d8be83fa1c758c7b701987a7dc30bc8 100644 (file)
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,3 +1,8 @@
+2020-04-19  Uroš Bizjak  <ubizjak@gmail.com>
+
+       * config/i386/sfp-exceptions.c (__sfp_handle_exceptions) [__SSE_MATH__]:
+       Remove unneeded assignments to volatile memory.
+
 2020-04-01  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
        Backport from mainline

diff --git a/libgcc/config/i386/sfp-exceptions.c b/libgcc/config/i386/sfp-exceptions.c
index a6c56392acdaf18306bc496ccee82dc38ad7677a..de4a2e0610203d16606a77e1e279c8c1d18adcec 100644 (file)
--- a/libgcc/config/i386/sfp-exceptions.c
+++ b/libgcc/config/i386/sfp-exceptions.c
@@ -48,9 +48,7 @@ __sfp_handle_exceptions (int _fex)
     {
       float f = 0.0f;
 #ifdef __SSE_MATH__
-      volatile float r __attribute__ ((unused));
       asm volatile ("%vdivss\t{%0, %d0|%d0, %0}" : "+x" (f));
-      r = f; /* Needed to trigger exception.   */
 #else
       asm volatile ("fdiv\t{%y0, %0|%0, %y0}" : "+t" (f));
       /* No need for fwait, exception is triggered by emitted fstp.  */
@@ -68,9 +66,7 @@ __sfp_handle_exceptions (int _fex)
     {
       float f = 1.0f, g = 0.0f;
 #ifdef __SSE_MATH__
-      volatile float r __attribute__ ((unused));
       asm volatile ("%vdivss\t{%1, %d0|%d0, %1}" : "+x" (f) : "xm" (g));
-      r = f; /* Needed to trigger exception.   */
 #else
       asm volatile ("fdivs\t%1" : "+t" (f) : "m" (g));
       /* No need for fwait, exception is triggered by emitted fstp.  */
@@ -96,9 +92,7 @@ __sfp_handle_exceptions (int _fex)
     {
       float f = 1.0f, g = 3.0f;
 #ifdef __SSE_MATH__
-      volatile float r __attribute__ ((unused));
       asm volatile ("%vdivss\t{%1, %d0|%d0, %1}" : "+x" (f) : "xm" (g));
-      r = f; /* Needed to trigger exception.   */
 #else
       asm volatile ("fdivs\t%1" : "+t" (f) : "m" (g));
       /* No need for fwait, exception is triggered by emitted fstp.  */

diff --git a/libgfortran/ChangeLog b/libgfortran/ChangeLog
index 01aa551b9146ace3dfe80e9bdcb8829fd3038736..946c9f0100b7b2e62f5d78b3b2c35cb7031a52df 100644 (file)
--- a/libgfortran/ChangeLog
+++ b/libgfortran/ChangeLog
@@ -1,3 +1,8 @@
+2020-04-19  Uroš Bizjak  <ubizjak@gmail.com>
+
+       * config/fpu-387.h (local_feraiseexcept) [__SSE_MATH__]:
+       Remove unneeded assignments to volatile memory.
+
 2020-03-12  Release Manager
 
        * GCC 9.3.0 released.

diff --git a/libgfortran/config/fpu-387.h b/libgfortran/config/fpu-387.h
index a2f4281d0c5b7c0accaddf1624a9aebbaeede095..bf4d78586c9c7c5ecb36eb322ba6f55a9dbed0f2 100644 (file)
--- a/libgfortran/config/fpu-387.h
+++ b/libgfortran/config/fpu-387.h
@@ -103,9 +103,7 @@ local_feraiseexcept (int excepts)
     {
       float f = 0.0f;
 #ifdef __SSE_MATH__
-      volatile float r __attribute__ ((unused));
       __asm__ __volatile__ ("%vdivss\t{%0, %d0|%d0, %0}" : "+x" (f));
-      r = f; /* Needed to trigger exception.   */
 #else
       __asm__ __volatile__ ("fdiv\t{%y0, %0|%0, %y0}" : "+t" (f));
       /* No need for fwait, exception is triggered by emitted fstp.  */
@@ -123,9 +121,7 @@ local_feraiseexcept (int excepts)
     {
       float f = 1.0f, g = 0.0f;
 #ifdef __SSE_MATH__
-      volatile float r __attribute__ ((unused));
       __asm__ __volatile__ ("%vdivss\t{%1, %d0|%d0, %1}" : "+x" (f) : "xm" (g));
-      r = f; /* Needed to trigger exception.   */
 #else
       __asm__ __volatile__ ("fdivs\t%1" : "+t" (f) : "m" (g));
       /* No need for fwait, exception is triggered by emitted fstp.  */
@@ -151,9 +147,7 @@ local_feraiseexcept (int excepts)
     {
       float f = 1.0f, g = 3.0f;
 #ifdef __SSE_MATH__
-      volatile float r __attribute__ ((unused));
       __asm__ __volatile__ ("%vdivss\t{%1, %d0|%d0, %1}" : "+x" (f) : "xm" (g));
-      r = f; /* Needed to trigger exception.   */
 #else
       __asm__ __volatile__ ("fdivs\t%1" : "+t" (f) : "m" (g));
       /* No need for fwait, exception is triggered by emitted fstp.  */