If the return value doesn't fit in a single register rdx/edx can in some
cases be used in addition to rax/eax.
Doesn't affect any of the existing checkasm tests but might be useful later.
Also comment the relevant code a bit better.
---
tests/checkasm/x86/checkasm.asm | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/tests/checkasm/x86/checkasm.asm b/tests/checkasm/x86/checkasm.asm
index 377fd37..da19aa2 100644
--- a/tests/checkasm/x86/checkasm.asm
+++ b/tests/checkasm/x86/checkasm.asm
@@ -145,10 +145,15 @@ cglobal checked_call, 2,15,16,max_args*8+8
or r14, r5
%endif
+ ; Call fail_func() with a descriptive message to mark it as a failure
+ ; if the called function didn't preserve all callee-saved registers.
+ ; Save the return value located in rdx:rax first to prevent clobbering.
jz .ok
mov r9, rax
+ mov r10, rdx
lea r0, [error_message]
call fail_func
+ mov rdx, r10
mov rax, r9
.ok:
RET
@@ -182,9 +187,11 @@ cglobal checked_call, 1,7
or r3, r5
jz .ok
mov r3, eax
+ mov r4, edx
lea r0, [error_message]
mov [esp], r0
call fail_func
+ mov edx, r4
mov eax, r3
.ok:
add esp, max_args*4
--
1.8.3.2
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