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[patch,mips] avoid invalid register for JALR
- From: Sandra Loosemore <sandra at codesourcery dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>
- Cc: Richard Sandiford <rdsandiford at googlemail dot com>
- Date: Tue, 13 May 2014 14:08:35 -0600
- Subject: [patch,mips] avoid invalid register for JALR
- Authentication-results: sourceware.org; auth=none
When I was trying to benchmark another patch (which I'll be sending
along shortly) with CSiBE for -mabi=64, I ran into an assembler error
like this:
/tmp/ccJv2faG.s: Assembler messages:
/tmp/ccJv2faG.s:1605: Error: a destination register must be supplied
`jalr $31'
Indeed, GCC is generating invalid code here; the single-operand JALR
instruction doesn't permit the use of $31 because it is already the
implicit destination register. The attached patch introduces a new
register class JALR_REGS to represent the valid set of registers for
this instruction, and modifies the "c" register constraint to use it.
I had some difficulty in regression-testing this patch because of
unrelated problems on trunk in the past week -- at first I was getting
ICEs due to a null pointer dereference in tree code, then when I tried
again a couple days later trunk was not even building. So I ended up
testing this patch on a more stable 4.9.0 checkout modified to support
Mentor's extended set of mips-sde-elf multilibs instead.
OK to commit?
-Sandra
2014-05-13 Sandra Loosemore <sandra@codesourcery.com>
gcc/
* config/mips/mips.h (enum reg_class): Add JALR_REGS.
(REG_CLASS_NAMES): Add initializer for JALR_REGS.
(REG_CLASS_CONTENTS): Likewise.
* config/mips/constraints.md ("c"): Use JALR_REGS
instead of GR_REGS.
Index: gcc/config/mips/mips.h
===================================================================
--- gcc/config/mips/mips.h (revision 210372)
+++ gcc/config/mips/mips.h (working copy)
@@ -1840,6 +1840,7 @@ enum reg_class
PIC_FN_ADDR_REG, /* SVR4 PIC function address register */
V1_REG, /* Register $v1 ($3) used for TLS access. */
LEA_REGS, /* Every GPR except $25 */
+ JALR_REGS, /* integer registers except $31 */
GR_REGS, /* integer registers */
FP_REGS, /* floating point registers */
MD0_REG, /* first multiply/divide register */
@@ -1878,6 +1879,7 @@ enum reg_class
"PIC_FN_ADDR_REG", \
"V1_REG", \
"LEA_REGS", \
+ "JALR_REGS", \
"GR_REGS", \
"FP_REGS", \
"MD0_REG", \
@@ -1919,6 +1921,7 @@ enum reg_class
{ 0x02000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000 }, /* PIC_FN_ADDR_REG */ \
{ 0x00000008, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000 }, /* V1_REG */ \
{ 0xfdffffff, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000 }, /* LEA_REGS */ \
+ { 0x7fffffff, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000 }, /* JALR_REGS */ \
{ 0xffffffff, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000 }, /* GR_REGS */ \
{ 0x00000000, 0xffffffff, 0x00000000, 0x00000000, 0x00000000, 0x00000000 }, /* FP_REGS */ \
{ 0x00000000, 0x00000000, 0x00000001, 0x00000000, 0x00000000, 0x00000000 }, /* MD0_REG */ \
Index: gcc/config/mips/constraints.md
===================================================================
--- gcc/config/mips/constraints.md (revision 210372)
+++ gcc/config/mips/constraints.md (working copy)
@@ -50,7 +50,7 @@
;; for details.
(define_register_constraint "c" "TARGET_MIPS16 ? M16_REGS
: TARGET_USE_PIC_FN_ADDR_REG ? PIC_FN_ADDR_REG
- : GR_REGS"
+ : JALR_REGS"
"A register suitable for use in an indirect jump. This will always be
@code{$25} for @option{-mabicalls}.")