Hi All,
For the below code (test.c)
int foo()
{
printf("Hello World");
}
On linux :
ccpc -mcpu=e6500 -mno-altivec -mabi=no-altivec -D_WRS_HARDWARE_FP
-mabi=elfv2 -mcmodel=med -mhard-float -S test.c
linux asm :
the constant string fetched like
addis 3,2,.LC0@toc@ha
addi 3,3,.LC0@toc@l
where offset signed 32 bit used relatively to toc base on linux as
expected for the medium code model .
and the relocation entry will be generated by gas :
R_PPC64_TOC16_HA and R_PPC64_TOC16_LO
For Windows :
same command and windows asm looks like
la 3,.LC0@toc(2)
where offset used signed 16 bit used relatively to toc base why it so ?.
and the relocation entry will be :
R_PPC64_TOC16 (signed 16 bit offset )
why this difference and when we greping the .md file and we found
patterns (rs6000.md ) like
;; Largetoc support
(define_insn "*largetoc_high"
[(set (match_operand:DI 0 "gpc_reg_operand" "=b*r")
(high:DI
(unspec [(match_operand:DI 1 "" "")
(match_operand:DI 2 "gpc_reg_operand" "b")]
UNSPEC_TOCREL)))]
"TARGET_ELF && TARGET_CMODEL != CMODEL_SMALL"
"addis %0,%2,%1@toc@ha")
(define_insn "*largetoc_high_aix<mode>"
[(set (match_operand:P 0 "gpc_reg_operand" "=b*r")
(high:P
(unspec [(match_operand:P 1 "" "")
(match_operand:P 2 "gpc_reg_operand" "b")]
UNSPEC_TOCREL)))]
"TARGET_XCOFF && TARGET_CMODEL != CMODEL_SMALL"
"addis %0,%1@u(%2)")
the above patterns answered the difference b/w windows and linux .
Questions to the expert is that using the medium code model ,how we
can get the same linux semantics on windows (without source code
changes) ?
or above distinguish patterns for a reason and which we are missing here ?
Thank you and awaiting for any comments
~Umesh
