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Refactor calling convention settings. (#304)

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Add a calling-convention setting to the `Flags` used as part of the
`TargetIsa`. This allows Cretonne code that generates calls to use the
correct convention, such as when emitting libcalls during legalization
or when the wasm frontend is decoding functions. This setting can be
overridden per-function.

This also adds "fast", "cold", and "fastcall" conventions, with "fast"
as the new default. Note that "fast" and "cold" are not intended to be
ABI-compatible across Cretonne versions.

This will also ensure Windows users will get an `unimplemented!` rather
than silent calling-convention mismatches, which reflects the fact that
Windows calling conventions are not yet implemented.

This also renames SpiderWASM, which isn't camel-case, to Baldrdash,
which is, and which is also a more relevant name.
This commit is contained in:
Dan Gohman
2018-04-22 21:35:18 -07:00
committed by GitHub
parent 8a9e4b9cff
commit c5b15c2396
38 changed files with 226 additions and 161 deletions
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2
cranelift/docs/heapex-dyn.cton
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@@ -1,6 +1,6 @@
test verifier
function %add_members(i32) -> f32 spiderwasm {
function %add_members(i32) -> f32 baldrdash {
gv0 = vmctx+64
gv1 = vmctx+72
heap0 = dynamic gv0, min 0x1000, bound gv1, guard 0

2
cranelift/docs/heapex-sm32.cton
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@@ -1,6 +1,6 @@
test verifier
function %add_members(i32) -> f32 spiderwasm {
function %add_members(i32) -> f32 baldrdash {
gv0 = vmctx+64
heap0 = static gv0, min 0x1000, bound 0x10_0000, guard 0x1000

2
cranelift/docs/heapex-sm64.cton
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@@ -1,6 +1,6 @@
test verifier
function %add_members(i32) -> f32 spiderwasm {
function %add_members(i32) -> f32 baldrdash {
gv0 = vmctx+64
heap0 = static gv0, min 0x1000, bound 0x1_0000_0000, guard 0x8000_0000

23
cranelift/docs/langref.rst
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@@ -399,7 +399,28 @@ convention:
param : type [paramext] [paramspecial]
paramext : "uext" | "sext"
paramspecial : "sret" | "link" | "fp" | "csr" | "vmctx"
callconv : "system_v" | "spiderwasm"
callconv : "fast" | "cold" | "system_v" | "fastcall" | "baldrdash"
A function's calling convention determines exactly how arguments and return
values are passed, and how stack frames are managed. Since all of these details
depend on both the instruction set /// architecture and possibly the operating
system, a function's calling convention is only fully determined by a
`(TargetIsa, CallConv)` tuple.
========== ===========================================
Name Description
========== ===========================================
fast not-ABI-stable convention for best performance
cold not-ABI-stable convention for infrequently executed code
system_v System V-style convention used on many platforms
fastcall Windows "fastcall" convention, also used for x64 and ARM
baldrdash SpiderMonkey WebAssembly convention
========== ===========================================
The "not-ABI-stable" conventions do not follow an external specification and
may change between versions of Cretonne.
The "fastcall" convention is not yet implemented.
Parameters and return values have flags whose meaning is mostly target
dependent. These flags support interfacing with code produced by other