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authorDavid S. Miller <davem@davemloft.net>2012-05-07 16:54:11 -0700
committerDavid S. Miller <davem@davemloft.net>2012-05-07 16:54:11 -0700
commit7f18b530e92914cfb5c5991e6610befc0444de40 (patch)
treef4e5250e01c72d4ed64b40e7224d08d45e5e8b89 /sysdeps/sparc
parent20f244a03fda84d1556674584b340e2459ef3d99 (diff)
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Fix sparc libm when all of glibc is built with -frounding-math.
[BZ #14074] * sysdeps/sparc/sysdep.h (SPARC_PIC_THUNK_CALL): New macro. (SETUP_PIC_REG): Use it. (SETUP_PIC_REG_LEAF): Use it.
Diffstat (limited to 'sysdeps/sparc')
-rw-r--r--sysdeps/sparc/sysdep.h25
1 files changed, 19 insertions, 6 deletions
diff --git a/sysdeps/sparc/sysdep.h b/sysdeps/sparc/sysdep.h
index 2702620be6..bcffec94f0 100644
--- a/sysdeps/sparc/sysdep.h
+++ b/sysdeps/sparc/sysdep.h
@@ -58,21 +58,34 @@ __sparc_get_pc_thunk.reg: \
.previous; \
.endif;
-/* Even when v9 we use a call sequence instead of using "rd %pc" because
+/* The "-4" and "+4" offsets against _GLOBAL_OFFSET_TABLE_ are
+ critical since they represent the offset from the thunk call to the
+ instruction containing the _GLOBAL_OFFSET_TABLE_ reference.
+ Therefore these instructions cannot be moved around without
+ appropriate adjustments to those offsets.
+
+ Furthermore, these expressions are special in another regard. When
+ the assembler sees a reference to _GLOBAL_OFFSET_TABLE_ inside of
+ a %hi() or %lo(), it emits a PC-relative relocation. This causes
+ R_SPARC_HI22 to turn into R_SPARC_PC22, and R_SPARC_LO10 to turn into
+ R_SPARC_PC10, respectively.
+
+ Even when v9 we use a call sequence instead of using "rd %pc" because
RDPC is extremely expensive and incurs a full pipeline flush. */
-#define SETUP_PIC_REG(reg) \
- SPARC_PIC_THUNK(reg) \
+#define SPARC_PIC_THUNK_CALL(reg) \
sethi %hi(_GLOBAL_OFFSET_TABLE_-4), %##reg; \
call __sparc_get_pc_thunk.reg; \
or %##reg, %lo(_GLOBAL_OFFSET_TABLE_+4), %##reg;
+#define SETUP_PIC_REG(reg) \
+ SPARC_PIC_THUNK(reg) \
+ SPARC_PIC_THUNK_CALL(reg)
+
#define SETUP_PIC_REG_LEAF(reg, tmp) \
SPARC_PIC_THUNK(reg) \
- sethi %hi(_GLOBAL_OFFSET_TABLE_-4), %##reg; \
mov %o7, %##tmp; \
- call __sparc_get_pc_thunk.reg; \
- or %##reg, %lo(_GLOBAL_OFFSET_TABLE_+4), %##reg; \
+ SPARC_PIC_THUNK_CALL(reg); \
mov %##tmp, %o7;
#undef ENTRY