Patchwork [i386] : Use __builtin_ia32_fxsave in crtfastmath.c

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Submitter Uros Bizjak
Date Oct. 26, 2012, 5:53 p.m.
Message ID <CAFULd4aV4e80yREODge1RphuZu6B9P_ZSU6vJpvU=6ZrQ4TK+A@mail.gmail.com>
Download mbox | patch
Permalink /patch/194550/
State New
Headers show

Comments

Uros Bizjak - Oct. 26, 2012, 5:53 p.m.
Hello!

Attached patch introduces __builtin_ia32_fxsave to crtfastmath.c. In
addition, it clears only fxsave.mxcsr_mask, as we will look at this
field only. Also, we don't have to execute additional stmxcsr, since
fxsave also saves this register.

2012-10-26  Uros Bizjak  <ubizjak@gmail.com>

	* config/i386/crtfastmath.c (set_fast_math): Use __builtin_ia32_fxsave.
	Clear only fxsave.mxcsr_mask.  Use saved mxcsr from fxsave structure
	when appropriate.  Correct structure element types.
	* config/i386/t-crtfm (crtfastmath.o): Compile with -mfxsr, remove
	-minline-all-stringops from compile flags.

Patch was bootstrapped and regression tested on x86_64-pc-linux-gnu {,-m32}.

Committed to mainline SVN.

Uros.

Patch

Index: config/i386/crtfastmath.c
===================================================================
--- config/i386/crtfastmath.c	(revision 192841)
+++ config/i386/crtfastmath.c	(working copy)
@@ -91,36 +91,41 @@  set_fast_math (void)
 	return;
 #endif /* __sun__ && __svr4__ */
 
-      mxcsr = __builtin_ia32_stmxcsr () | MXCSR_FTZ;
-
       if (edx & bit_FXSAVE)
 	{
 	  /* Check if DAZ is available.  */
 	  struct
 	    {
-	      unsigned short int cwd;
-	      unsigned short int swd;
-	      unsigned short int twd;
-	      unsigned short int fop;
-	      long int fip;
-	      long int fcs;
-	      long int foo;
-	      long int fos;
-	      long int mxcsr;
-	      long int mxcsr_mask;
-	      long int st_space[32];
-	      long int xmm_space[32];
-	      long int padding[56];
+	      unsigned short cwd;
+	      unsigned short swd;
+	      unsigned short twd;
+	      unsigned short fop;
+	      unsigned int fip;
+	      unsigned int fcs;
+	      unsigned int foo;
+	      unsigned int fos;
+	      unsigned int mxcsr;
+	      unsigned int mxcsr_mask;
+	      unsigned int st_space[32];
+	      unsigned int xmm_space[32];
+	      unsigned int padding[56];
 	    } __attribute__ ((aligned (16))) fxsave;
 
-	  __builtin_memset (&fxsave, 0, sizeof (fxsave));
+	  /* This is necessary since some implementations of FXSAVE
+	     do not modify reserved areas within the image.  */
+	  fxsave.mxcsr_mask = 0;
 
-	  asm volatile ("fxsave %0" : "=m" (fxsave) : "m" (fxsave));
+	  __builtin_ia32_fxsave (&fxsave);
 
+	  mxcsr = fxsave.mxcsr;
+
 	  if (fxsave.mxcsr_mask & MXCSR_DAZ)
 	    mxcsr |= MXCSR_DAZ;
 	}
+      else
+	mxcsr = __builtin_ia32_stmxcsr ();
 
+      mxcsr |= MXCSR_FTZ;
       __builtin_ia32_ldmxcsr (mxcsr);
     }
 #else
Index: config/i386/t-crtfm
===================================================================
--- config/i386/t-crtfm	(revision 192841)
+++ config/i386/t-crtfm	(working copy)
@@ -1,4 +1,4 @@ 
 # This is an endfile, Use -minline-all-stringops to ensure
 # that __builtin_memset doesn't refer to the lib function memset().
 crtfastmath.o: $(srcdir)/config/i386/crtfastmath.c
-	$(gcc_compile) -msse -minline-all-stringops -c $<
+	$(gcc_compile) -mfxsr -msse -c $<