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Re: [PATCH, rs6000] PR target/57150, do not use VSX instructions for long double caller saves


On Fri, 3 May 2013, Michael Meissner wrote:

> 2013-05-03  Michael Meissner  <meissner@linux.vnet.ibm.com>
> 
> 	PR target/57150
> 	* config/rs6000/rs6000.h (HARD_REGNO_CALLER_SAVE_MODE): Use DFmode
> 	to save TFmode registers and DImode to save TImode registers for
> 	caller save operations.
> 	(HARD_REGNO_CALL_PART_CLOBBERED): TFmode and TDmode do not need to
> 	mark being partially clobbered since they only use the first
> 	double word.
> 
> 	* config/rs6000/rs6000.c (rs6000_init_hard_regno_mode_ok): TFmode
> 	and TDmode only use the upper 64-bits of each VSX register.

That change has the effect that reload thinks TFmode (and no doubt
TDmode) only takes two registers even when in general registers,
causing a segfault in glibc's test-ldouble built for soft float.

I'm testing this patch (this diff is against 4.8 branch) to fix this;
at least, it fixes the glibc testing issue.  Since the original patch
went on 4.7 and 4.8 branches as well as trunk, I propose this patch
for the branches as well as trunk.  You may wish to test it in your
original VSX configuration.

2013-07-03  Joseph Myers  <joseph@codesourcery.com>

	* config/rs6000/rs6000.c (rs6000_init_hard_regno_mode_ok): Only
	adjust register size for TDmode and TFmode for VSX registers.

Index: config/rs6000/rs6000.c
===================================================================
--- config/rs6000/rs6000.c	(revision 200641)
+++ config/rs6000/rs6000.c	(working copy)
@@ -2190,7 +2190,8 @@ rs6000_init_hard_regno_mode_ok (bool global_init_p
 	  int reg_size2 = reg_size;
 
 	  /* TFmode/TDmode always takes 2 registers, even in VSX.  */
-	  if (m == TDmode || m == TFmode)
+	  if (TARGET_VSX && VSX_REG_CLASS_P (c)
+	      && (m == TDmode || m == TFmode))
 	    reg_size2 = UNITS_PER_FP_WORD;
 
 	  rs6000_class_max_nregs[m][c]

-- 
Joseph S. Myers
joseph@codesourcery.com


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