[PATCH] D124435: [X86] Always extend the integer parameters in callee

[LiuChen via Phabricator via cfe-commits]

LiuChen3 added inline comments.


================
Comment at: clang/lib/CodeGen/CGCall.cpp:2451
+      // attribute to the callee.
+      if (AttrOnCallSite || AI.getKind() == ABIArgInfo::Extend) {
+        if (AI.isSignExt())
----------------
pengfei wrote:
> Does the change affect Windows? Seems Win64 doesn't extend on caller. https://godbolt.org/z/c95hvvsWf
No.  This patch didn't nothing for Win64 ABI.


================
Comment at: clang/test/CodeGen/X86/integer_argument_passing.c:2
+// RUN: %clang_cc1 -O2 -triple -x86_64-linux-gnu %s -emit-llvm -o - | FileCheck %s --check-prefixes=EXTEND,CHECK
+// RUN: %clang_cc1 -O2 -triple -i386-linux-gnu %s -emit-llvm -o - | FileCheck %s --check-prefixes=EXTEND,CHECK
+// RUN: %clang_cc1 -O2 -triple -i386-pc-win32 %s -emit-llvm -o - | FileCheck %s --check-prefixes=EXTEND,CHECK
----------------
pengfei wrote:
> Maybe we can remove the tests for i386 given it's only for 64 bits ABI?
According to the meaning of `ConservativeExtend`, I think the 32bit ABI needs to be modified as well:
https://godbolt.org/z/W1Ma1T3f3
The dump of currently clang-cl:
```
_square:
        movb    4(%esp), %al
        mulb    %al
        mulb    8(%esp)
        retl

        .def    _baz;
        .scl    2;
        .type   32;
        .endef
        .section        .text,"xr",one_only,_baz
        .globl  _baz
        .p2align        4, 0x90
_baz:
        movswl  4(%esp), %eax
        pushl   %eax
        calll   _bar
        addl    $4, %esp
        retl
```
Of course with this patch the behavior of clang-cl is still different from cl.exe, but I think it fits the meaning of `ConservativeExtend`.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D124435/new/

https://reviews.llvm.org/D124435