On Fri, 2022-03-04 at 15:18 +0800, xucheng...@loongson.cn wrote:
> * config/loongarch/loongarch.md: New file.
An ICE happens building OpenSSH-8.9p1. Investigation shows it's caused
by the flag "-fzero-call-used-regs=". It's because the compiler
attempts to clear FCCx registers but can't figure out how.
This flag also triggers ICE for other targets (for example, PR 104820
for MIPS), and the related tests (zero-scratch-regs-{8,9,10,11}.c) are
marked dg-skip for many targets.
But it's unfortunate that packages like OpenSSH have already start to
use this flag... I guess they just enabled it once they saw it was
working for i386 :(. So it's better to solve the problem for a new
target.
A "quick fix" is adding an insn to clear FCCx. This is enough to build
OpenSSH and make zero-scratch-regs-{8,9,10,11}.c PASS.
diff --git a/gcc/config/loongarch/loongarch.md
b/gcc/config/loongarch/loongarch.md
index a9a8bc4b038..76c5ded9fe4 100644
--- a/gcc/config/loongarch/loongarch.md
+++ b/gcc/config/loongarch/loongarch.md
@@ -2020,6 +2020,12 @@
DONE;
})
+;; Clear one FCC register
+(define_insn "movfcc" [(set (match_operand:FCC 0 "register_operand" "=z")
+ (const_int 0))]
+ ""
+ "movgr2cf\t%0,$r0")
+
;; Conditional move instructions.
(define_insn "*sel<code><GPR:mode>_using_<GPR2:mode>"
--
Xi Ruoyao <xry...@mengyan1223.wang>
School of Aerospace Science and Technology, Xidian University
