[PATCH, i386]: Additional fix for PR62599 with -mcmodel=medium -fpic

[Uros Bizjak]

Hello!

testsuite/gcc.target/i386/pr61599-{1,2}.c testcases expose a failure
with -mcmodel -fpic, where:

/tmp/ccfpoxHY.o: In function `bar':
pr61599-2.c:(.text+0xe): relocation truncated to fit: R_X86_64_PC32
against symbol `a' defined in LARGE_COMMON section in /tmp/ccKTKST2.o
collect2: error: ld returned 1 exit status
compiler exited with status 1

CM_MEDIUM_PIC code model assumes that code+got/plt fits in a 31 bit
region, data is unlimited. Based on these assumptions, code should be
accessed via R_X86_64_GOT64.

Attached patch uses UNSPEC_GOT instead of UNSPEC_GOTPCREL also for
CM_MEDIUM_PIC.

2016-05-12  Uros Bizjak  <ubizjak@gmail.com>

    PR target/61599
    * config/i386/i386.c (legitimize_pic_address): Do not use
    UNSPEC_GOTPCREL for CM_MEDIUM_PIC code model.

Patch was bootstrapped on x86_64-linux-gnu and regression tested with
-mcmodel=medium -fpic.

Jakub, H.J., do you have any comments on the patch?

Uros.
-------------- next part --------------
Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c	(revision 236182)
+++ config/i386/i386.c	(working copy)
@@ -15475,7 +15475,7 @@ legitimize_pic_address (rtx orig, rtx reg)
 	  new_rtx = gen_rtx_UNSPEC (Pmode, gen_rtvec (1, addr), UNSPEC_PCREL);
 	  new_rtx = gen_rtx_CONST (Pmode, new_rtx);
 	}
-      else if (TARGET_64BIT && ix86_cmodel != CM_LARGE_PIC)
+      else if (TARGET_64BIT && ix86_cmodel == CM_SMALL_PIC)
 	{
 	  new_rtx = gen_rtx_UNSPEC (Pmode, gen_rtvec (1, addr),
 				    UNSPEC_GOTPCREL);