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or1k: Fix issue with set_got clobbering LR (r9)

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When compiling glibc we found that the GOT register was being allocated
r9 when the instruction was still set_got_tmp.  That is a problem
because r9 is the Link Register (LR) in OpenRISC which is used/clobbered
in set_got.  We cannot use r9 as the GOT register.  Also, we cannot
simply say set_got_tmp clobbers r9 as this is the reason for having the
temporary set_got_tmp.

Fix by using a register class constraint that does not allow r9 during
register allocation.

gcc/ChangeLog:

        * config/or1k/constraints.md (t): New constraint.
        * config/or1k/or1k.h (GOT_REGS): New register class.
        * config/or1k/or1k.md (set_got_tmp, set_got): Use t contraint.

From-SVN: r275242
This commit is contained in:
Stafford Horne 2019-08-31 06:00:56 +00:00 • committed by Stafford Horne
parent 3ba155dd19
commit fd631eb5a7
4 changed files with 15 additions and 2 deletions
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6
gcc/ChangeLog
View file

@ -1,3 +1,9 @@
2019-08-31 Stafford Horne <shorne@gmail.com>
* config/or1k/constraints.md (t): New constraint.
* config/or1k/or1k.h (GOT_REGS): New register class.
* config/or1k/or1k.md (set_got_tmp, set_got): Use t contraint.
2019-08-30 Jim Wilson <jimw@sifive.com>
* config/riscv/riscv.c (riscv_option_override): If -msave-restore

4
gcc/config/or1k/constraints.md
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@ -25,6 +25,7 @@
; We use:
; c - sibcall registers
; d - double pair base registers (excludes r0, r30 and r31 which overflow)
; t - got address registers (excludes LR (r9) which is clobbered by set_got)
; I - constant signed 16-bit
; K - constant unsigned 16-bit
; M - constant signed 16-bit shifted left 16-bits (l.movhi)
@ -36,6 +37,9 @@
(define_register_constraint "d" "DOUBLE_REGS"
"Registers which can be used for double reg pairs.")
(define_register_constraint "t" "GOT_REGS"
"Registers which can be used to store the Global Offset Table (GOT) address.")
;; Immediates
(define_constraint "I"
"A signed 16-bit immediate in the range -32768 to 32767."

3
gcc/config/or1k/or1k.h
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@ -190,6 +190,7 @@ enum reg_class
NO_REGS,
SIBCALL_REGS,
DOUBLE_REGS,
GOT_REGS,
GENERAL_REGS,
FLAG_REGS,
ALL_REGS,
@ -202,6 +203,7 @@ enum reg_class
"NO_REGS", \
"SIBCALL_REGS", \
"DOUBLE_REGS", \
"GOT_REGS", \
"GENERAL_REGS", \
"FLAG_REGS", \
"ALL_REGS" }
@ -215,6 +217,7 @@ enum reg_class
{ { 0x00000000, 0x00000000 }, \
{ SIBCALL_REGS_MASK, 0 }, \
{ 0x7f7ffffe, 0x00000000 }, \
{ 0xfffffdff, 0x00000000 }, \
{ 0xffffffff, 0x00000003 }, \
{ 0x00000000, 0x00000004 }, \
{ 0xffffffff, 0x00000007 } \

4
gcc/config/or1k/or1k.md
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@ -706,7 +706,7 @@
;; set_got pattern below. This works because the set_got_tmp insn is the
;; first insn in the stream and that it isn't moved during RA.
(define_insn "set_got_tmp"
[(set (match_operand:SI 0 "register_operand" "=r")
[(set (match_operand:SI 0 "register_operand" "=t")
(unspec_volatile:SI [(const_int 0)] UNSPECV_SET_GOT))]
""
{
@ -715,7 +715,7 @@
;; The insn to initialize the GOT.
(define_insn "set_got"
[(set (match_operand:SI 0 "register_operand" "=r")
[(set (match_operand:SI 0 "register_operand" "=t")
(unspec:SI [(const_int 0)] UNSPEC_SET_GOT))
(clobber (reg:SI LR_REGNUM))]
""