https://sourceware.org/bugzilla/show_bug.cgi?id=25438
Bug ID: 25438
Summary: x86 MOVZ* anomalies for unusual/wrong operand
combinations
Product: binutils
Version: unspecified
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: gas
Assignee: unassigned at sourceware dot org
Reporter: jbeulich at suse dot com
Target Milestone: ---
The tests proposed to be added by
https://sourceware.org/ml/binutils/2019-12/msg00354.html
demonstrate some inconsistencies which get addressed by the next patch of the
series:
https://sourceware.org/ml/binutils/2019-12/msg00346.html
The condensed differences from before the patch (and 2.33.1 behavior) and after
it can be seen in the following diff of the respective listing files:
--- movx.l
+++ movx.l
@@ -7,39 +7,43 @@
4 movsbw %al, %ecx
5 movsbl %al, %cx
6
- 7 ???? 660FB6C8 movzbw %al, %ecx
- 8 ???? 0FB6C8 movzbl %al, %cx
+ 7 ???? 0FB6C8 movzbw %al, %ecx
+**** Warning: using `%cx' instead of `%ecx' due to `w' suffix
+ 8 ???? 660FB6C8 movzbl %al, %cx
+**** Warning: using `%ecx' instead of `%cx' due to `l' suffix
9
10 .code32
11 code32:
12 movsbw %al, %ecx
13 movsbl %al, %cx
14
- 15 ???? 0FB6C8 movzbw %al, %ecx
- 16 ???? 660FB6C8 movzbl %al, %cx
+ 15 ???? 660FB6C8 movzbw %al, %ecx
+**** Warning: using `%cx' instead of `%ecx' due to `w' suffix
+ 16 ???? 0FB6C8 movzbl %al, %cx
+**** Warning: using `%ecx' instead of `%cx' due to `l' suffix
17
18 .code64
19 code64:
20 movsbw %al, %ecx
21 movsbw %al, %rcx
22
- 23 ???? 0FB6C8 movzbw %al, %ecx
- 24 ???? 480FB6C8 movzbw %al, %rcx
+ 23 movzbw %al, %ecx
+ 24 movzbw %al, %rcx
25
26 movsbl %al, %cx
27 movsbl %al, %rcx
28
- 29 ???? 660FB6C8 movzbl %al, %cx
- 30 ???? 480FB6C8 movzbl %al, %rcx
+ 29 movzbl %al, %cx
+ 30 movzbl %al, %rcx
31
32 movsbq %al, %cx
33 movsbq %al, %ecx
34
- 35 ???? 660FB6C8 movzbq %al, %cx
- 36 ???? 0FB6C8 movzbq %al, %ecx
+ 35 movzbq %al, %cx
+ 36 movzbq %al, %ecx
37
38 movswl %ax, %rcx
39 movswq %ax, %ecx
40
- 41 ???? 480FB7C8 movzwl %ax, %rcx
- 42 ???? 0FB7C8 movzwq %ax, %ecx
+ 41 movzwl %ax, %rcx
+ 42 movzwq %ax, %ecx
IOW,
- for 32- and 16-bit code generated code and emitted diagnostics get brought in
sync with that for other insns, i.e. suffix trumps register size,
- for 64-bit code emitted diagnostics get brought in sync with that for other
insns, i.e. mismatched suffix and register size are not allowed,
- for 64-bit code additionally MOVZ* behavior no longer differs from MOVS* one,
except for the precise wording of the error ("incorrect register ... used with
... suffix" vs "operand size mismatch").
Of course this example additionally demonstrates that MOVS* handling in 32- and
16-bit modes still won't be in line with all other insns, due to there not
being true suffixes in the insn templates. But that's a separate topic,
adjustment to which was previously attempted but rejected by the maintainer.
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