[PATCH] PR45070: Fix wrong epilogue code for cortex-m0/Os

["Bin Cheng" <bin dot cheng at arm dot com>]

Hi,
I found below regression tests are failed on trunk for cortex-m0/Os:

FAIL: gcc.c-torture/execute/pr45070.c execution,  -Os
FAIL: gcc.dg/compat/struct-layout-1 c_compat_x_tst.o-c_compat_y_tst.o
execute
FAIL: gcc.dg/compat/struct-return-2 c_compat_x_tst.o-c_compat_y_tst.o
execute
FAIL: tmpdir-gcc.dg-struct-layout-1/t001 c_compat_x_tst.o-c_compat_y_tst.o
execute
WARNING: program timed out.
FAIL: tmpdir-gcc.dg-struct-layout-1/t002 c_compat_x_tst.o-c_compat_y_tst.o
execute
FAIL: tmpdir-gcc.dg-struct-layout-1/t024 c_compat_x_tst.o-c_compat_y_tst.o
execute
FAIL: tmpdir-gcc.dg-struct-layout-1/t025 c_compat_x_tst.o-c_compat_y_tst.o
execute
FAIL: tmpdir-gcc.dg-struct-layout-1/t027 c_compat_x_tst.o-c_compat_y_tst.o
execute
FAIL: tmpdir-gcc.dg-struct-layout-1/t028 c_compat_x_tst.o-c_compat_y_tst.o
execute

Seems the patch for pr45070 does not cover Thumb1 instruction set, here
comes this patch fixing the issue.

It is caused by wrong epilogue generated for cortex-m0/Os. In function
thumb1_extra_regs_pushed, gcc calculates reg_base as following, which does
not honor return value of size less than 4 bytes, resulting in wrong pop
sequences.
	reg_base = arm_size_return_regs () / UNITS_PER_WORD;

I ran regression test with/without Os for cortex-m0 and everything is ok.
Ok for trunk and 4.7/4.6 release branches?

Thanks.


2012-09-04  Bin Cheng  <bin.cheng@arm.com>

	PR target/45070
	* config/arm/arm.c (thumb1_extra_regs_pushed): Handle return value
of size
	less than 4 bytes by using macro ARM_NUM_INTS.
	(thumb1_unexpanded_epilogue): Use macro ARM_NUM_INTS.

Attachment: fix-m0-Os-wrong-epilogue-20120904.txt
Description: Text document