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Use single index for param register allocation for windows callconv (… (#693)

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* Use single index for param register allocation for windows callconv (#691)

The used registers depend entirely on the parameter index (1st, 2nd, 3rd, 4th, ... param)
and we cannot shift unused registers to other indexes, if they are not designated for
the use for that parameter index.
This commit is contained in:
Steffen Butzer
2019-03-05 12:17:41 +01:00
committed by Benjamin Bouvier
parent 2f2626f4b3
commit 2a519092a0
2 changed files with 18 additions and 3 deletions
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15
cranelift/codegen/src/isa/x86/abi.rs
View File

@@ -115,9 +115,18 @@ impl ArgAssigner for Args {
}
// Try to use an FPR.
if ty.is_float() && self.fpr_used < self.fpr_limit {
let reg = FPR.unit(self.fpr_used);
self.fpr_used += 1;
let fpr_offset = if self.call_conv == CallConv::WindowsFastcall {
// Float and general registers on windows share the same parameter index.
// The used register depends entirely on the parameter index: Even if XMM0
// is not used for the first parameter, it cannot be used for the second parameter.
debug_assert_eq!(self.fpr_limit, self.gpr.len());
&mut self.gpr_used
} else {
&mut self.fpr_used
};
if ty.is_float() && *fpr_offset < self.fpr_limit {
let reg = FPR.unit(*fpr_offset);
*fpr_offset += 1;
return ArgumentLoc::Reg(reg).into();
}

6
cranelift/filetests/filetests/isa/x86/windows_fastcall_x64.clif
View File

@@ -31,3 +31,9 @@ ebb0(v0: i64, v1: i64, v2: i64, v3: i64, v4: i64):
return
}
; check: function %five_args(i64 [%rcx], i64 [%rdx], i64 [%r8], i64 [%r9], i64 [32], i64 fp [%rbp]) -> i64 fp [%rbp] windows_fastcall {
function %mixed_int_float(i64, f64, i64, f32) windows_fastcall {
ebb0(v0: i64, v1: f64, v2: i64, v3: f32):
return
}
; check: function %mixed_int_float(i64 [%rcx], f64 [%xmm1], i64 [%r8], f32 [%xmm3], i64 fp [%rbp]) -> i64 fp [%rbp] windows_fastcall {