When allocating stack space with a larger alignment than the known stack
alignment a temporary register is used for storing the stack pointer.
Ensure that this isn't one of the registers used for passing arguments.
---
libavutil/x86/x86inc.asm | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/libavutil/x86/x86inc.asm b/libavutil/x86/x86inc.asm
index fc58b74..7d6c171 100644
--- a/libavutil/x86/x86inc.asm
+++ b/libavutil/x86/x86inc.asm
@@ -386,8 +386,11 @@ DECLARE_REG_TMP_SIZE 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14
%if %1 != 0 && required_stack_alignment > STACK_ALIGNMENT
%if %1 > 0
%assign regs_used (regs_used + 1)
- %elif ARCH_X86_64 && regs_used == num_args && num_args <= 4 +
UNIX64 * 2
- %warning "Stack pointer will overwrite register argument"
+ %endif
+ %if ARCH_X86_64 && regs_used < 5 + UNIX64 * 3
+ ; Ensure that we don't clobber any registers containing
arguments. For UNIX64 we also preserve r6 (rax)
+ ; since it's used as a hidden argument in vararg functions to
specify the number of vector registers used.
+ %assign regs_used 5 + UNIX64 * 3
%endif
%endif
%endif
--
1.9.1
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