The branch main has been updated by kib:
URL:
https://cgit.FreeBSD.org/src/commit/?id=cb991a228179639cc0568fdd5d4b4b07b6f47b5a
commit cb991a228179639cc0568fdd5d4b4b07b6f47b5a
Author: Konstantin Belousov <k...@freebsd.org>
AuthorDate: 2025-03-02 23:54:24 +0000
Commit: Konstantin Belousov <k...@freebsd.org>
CommitDate: 2025-03-04 04:24:59 +0000
amd64 csu: microoptimize startup
Reorder operations to reduce moving the values among registers.
Use the LEA instruction to combine arithmetic with the moves.
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D49206
---
lib/csu/amd64/crt1_s.S | 15 ++++++---------
1 file changed, 6 insertions(+), 9 deletions(-)
diff --git a/lib/csu/amd64/crt1_s.S b/lib/csu/amd64/crt1_s.S
index f7ea076d94f1..3ceea9289330 100644
--- a/lib/csu/amd64/crt1_s.S
+++ b/lib/csu/amd64/crt1_s.S
@@ -49,15 +49,12 @@ _start:
#ifdef GCRT
subq $16, %rsp
#endif
- movq %rsi, %rcx
- movq %rdi, %rsi /* argv = ap */
- addq $8, %rsi /* argv += 1 */
- movq %rdi, %rdx /* env = ap */
- addq $16, %rdx /* env += 2 */
- movslq (%rdi), %rax
- movl %eax, %edi /* argc = *(long *)(void *)ap */
- shlq $3, %rax
- addq %rax, %rdx /* env += argc */
+ movq %rsi, %rcx /* cleanup */
+ movslq (%rdi), %rax /* long *ap; tmpargc = *ap */
+ leaq 0x8(%rdi), %rsi /* argv = ap + 1 */
+ leaq 0x10(%rdi, %rax, 8), %rdx /* env = ap + 2 + tmpargc */
+ movl %eax, %edi /* argc = tmpargc */
+
#ifdef PIC
/*
* XXX. %rip relative addressing is not intended for use in the
