[clang] [llvm] [AArch64] Support preserve_none calling convention (PR #91046)

[Daniel Kiss via cfe-commits]

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@@ -0,0 +1,92 @@
+; RUN: sed -e "s/RETTYPE/void/;s/RETVAL//" %s | llc -mtriple=aarch64-apple-darwin | FileCheck --check-prefixes=ALL %s
+; RUN: sed -e "s/RETTYPE/i32/;s/RETVAL/undef/" %s | llc -mtriple=aarch64-apple-darwin | FileCheck --check-prefixes=ALL %s
+; RUN: sed -e "s/RETTYPE/\{i64\,i64\}/;s/RETVAL/undef/" %s | llc -mtriple=aarch64-apple-darwin | FileCheck --check-prefixes=ALL %s
+; RUN: sed -e "s/RETTYPE/double/;s/RETVAL/0./" %s | llc -mtriple=aarch64-apple-darwin | FileCheck --check-prefixes=ALL,DOUBLE %s
+
+; We don't need to save registers before using them inside preserve_none function.
+define preserve_nonecc RETTYPE @preserve_nonecc1(i64, i64, double, double) nounwind {
+entry:
+;ALL-LABEL:   preserve_nonecc1
+;ALL:         ; %bb.0:
+;ALL-NEXT:    InlineAsm Start
+;ALL-NEXT:    InlineAsm End
+;DOUBLE-NEXT: movi d0, #0000000000000000
+;ALL-NEXT:    ret
+  call void asm sideeffect "", "~{x0},~{x1},~{x2},~{x3},~{x4},~{x5},~{x6},~{x7},~{x8},~{x9},~{x10},~{x11},~{x12},~{x13},~{x14},~{x15},~{x16},~{x17},~{x19},~{x20},~{x21},~{x22},~{x23},~{x24},~{x25},~{x26},~{x27},~{x28},~{d0},~{d1},~{d2},~{d3},~{d4},~{d5},~{d6},~{d7},~{d8},~{d9},~{d10},~{d11},~{d12},~{d13},~{d14},~{d15},~{d16}"()
+  ret RETTYPE RETVAL
+}
+
+; When calling a preserve_none function, all live registers must be saved and
+; restored around the function call.
+declare preserve_nonecc RETTYPE @bar(i64, i64, double, double)
----------------
DanielKristofKiss wrote:

NIT: maybe easier to follow like:

```suggestion
declare preserve_nonecc RETTYPE @preserve_nonecc2(i64, i64, double, double)
define void @bar() nounwind {
```

https://github.com/llvm/llvm-project/pull/91046