https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90049
Bug ID: 90049
Summary: Wrong expanding for a unsigned short ssa_name in
embedded assembly code.
Product: gcc
Version: 6.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: wangtao42 at huawei dot com
Target Milestone: ---
Created attachment 46143
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=46143&action=edit
testcase
A unsigned short ssa_name in embedded assembly code will be expanded to
subreg:HI, and without the bit extracting action. It will result in a wrong
assembly code.
The attachment is the testcase, and the command is as follows:
mips-sde-elf-gcc -O2 -S t2.c
And the result assembly code is:
func:
.frame $sp,0,$31 # vars= 0, regs= 0/0, args= 0, gp= 0
.mask 0x00000000,0
.fmask 0x00000000,0
lw $3,0($4)
lw $2,%gp_rel(g_b)($28)
srl $4,$3,24
sw $3,%gp_rel(g_a)($28)
ext $6,$2,0,17
sltu $7,$4,1
#APP
# 27 "t2.c" 1
addiu $5, $6, 0
movn $5, $3, $7
# 0 "" 2
#NO_APP
ins $2,$5,0,17
.set noreorder
.set nomacro
jr $31
sw $2,%gp_rel(g_b)($28)
It is wrong that the $3 is loaded a word from 0($4), and the $3 should be the
low 16bit of 0($4). I guess something wrong with expand_gimple_basic_block, and
this ignore should not be used in embedded assembly code:
5822 def_p = SINGLE_SSA_DEF_OPERAND (stmt, SSA_OP_DEF);
5823
5824 if (def_p != NULL)
5825 {
5826 /* Ignore this stmt if it is in the list of
5827 replaceable expressions. */
5828 if (SA.values
5829 && bitmap_bit_p (SA.values,
5830 SSA_NAME_VERSION (DEF_FROM_PTR
(def_p))))
5831 continue;
5832 }
5833 last = expand_gimple_stmt (stmt);
Please help to check this.
Thanks
