https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117312
--- Comment #17 from Uroš Bizjak <ubizjak at gmail dot com> ---
With the patch in PR117359 applied and testcase patched with:
--cut here--
--- pr117312.c 2024-10-30 10:50:04.921338850 +0100
+++ pr117312-new.c 2024-10-30 10:49:49.441488965 +0100
@@ -1,3 +1,6 @@
+register unsigned long current_stack_pointer asm ("%rsp");
+#define ASM_CALL_CONSTRAINT "+r" (current_stack_pointer)
+
/* Just an opaque data source */
static inline __attribute__((always_inline)) int get_random(void)
{
@@ -22,7 +25,7 @@
/* Clobbers [-16..-1](%rsp) */
/* "volatile" or a memory clobber doesn't seem to make any difference */
asm("push %2; pushf; pop %0; pop %1"
- : "=r" (y), "=r" (z)
+ : "=r" (y), "=r" (z), ASM_CALL_CONSTRAINT
: "r" (x)
: "memory");
the resulting asm differs in:
--- pr117312.s 2024-10-30 10:50:13.170258856 +0100
+++ pr117312-new.s 2024-10-30 10:50:28.517110031 +0100
@@ -1,4 +1,4 @@
- .file "pr117312.c"
+ .file "pr117312-new.c"
.text
.p2align 4
.globl asm_clobbers_redzone
@@ -6,115 +6,116 @@
asm_clobbers_redzone:
.LFB1:
.cfi_startproc
- movl %edi, %eax
+ subq $72, %rsp
+ .cfi_def_cfa_offset 80
#APP
-# 5 "pr117312.c" 1
+# 8 "pr117312-new.c" 1
rdrand %edx
# 0 "" 2
#NO_APP
- movl %edx, -72(%rsp)
+ movl %edx, (%rsp)
#APP
-# 5 "pr117312.c" 1
- rdrand %ecx
+# 8 "pr117312-new.c" 1
+ rdrand %eax
# 0 "" 2
#NO_APP
- movl %ecx, -68(%rsp)
+ movl %eax, 4(%rsp)
#APP
-# 5 "pr117312.c" 1
- rdrand %esi
+# 8 "pr117312-new.c" 1
+ rdrand %ecx
# 0 "" 2
#NO_APP
- movl %esi, -64(%rsp)
+ movl %ecx, 8(%rsp)
...
No redzone was used with the patched testcase.
