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rustc_trans: Disable landing pads on 32-bit MSVC
This is currently quite buggy in LLVM from what I can tell, so just disable it entirely. This commit also adds preliminary support, however, to actually target 32-bit MSVC by making sure the `rust_try_msvc_32.ll` file exists and wiring up exceptions to `_except_handler3` instead of `__C_specific_handler` (which doesn't exist on 32-bit).
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-6
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3 files changed

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‎src/librustc_trans/trans/base.rs

+8-1
Original file line numberDiff line numberDiff line change
@@ -752,7 +752,14 @@ pub fn invoke<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
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753753
pub fn need_invoke(bcx: Block) -> bool {
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if bcx.sess().no_landing_pads() {
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return false;
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return false
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}
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// Currently 32-bit MSVC unwinding is not super well implemented in LLVM, so
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// we avoid it entirely.
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if bcx.sess().target.target.options.is_like_msvc &&
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bcx.sess().target.target.arch == "x86" {
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return false
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}
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// Avoid using invoke if we are already inside a landing pad.

‎src/librustc_trans/trans/cleanup.rs

+7-5
Original file line numberDiff line numberDiff line change
@@ -851,8 +851,8 @@ impl<'blk, 'tcx> CleanupHelperMethods<'blk, 'tcx> for FunctionContext<'blk, 'tcx
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// an "exception", but for MSVC we want to force SEH. This means that we
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// can't actually have the personality function be our standard
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// `rust_eh_personality` function, but rather we wired it up to the
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// CRT's custom `__C_specific_handler` personality funciton, which
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// forces LLVM to consider landing pads as "landing pads for SEH".
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// CRT's custom personality function, which forces LLVM to consider
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// landing pads as "landing pads for SEH".
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let target = &self.ccx.sess().target.target;
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let llpersonality = match pad_bcx.tcx().lang_items.eh_personality() {
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Some(def_id) if !target.options.is_like_msvc => {
@@ -864,10 +864,12 @@ impl<'blk, 'tcx> CleanupHelperMethods<'blk, 'tcx> for FunctionContext<'blk, 'tcx
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match *personality {
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Some(llpersonality) => llpersonality,
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None => {
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let name = if target.options.is_like_msvc {
868-
"__C_specific_handler"
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} else {
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let name = if !target.options.is_like_msvc {
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"rust_eh_personality"
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} else if target.arch == "x86" {
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"_except_handler3"
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} else {
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"__C_specific_handler"
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};
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let fty = Type::variadic_func(&[], &Type::i32(self.ccx));
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let f = declare::declare_cfn(self.ccx, name, fty,

‎src/rt/rust_try_msvc_32.ll

+42
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,42 @@
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; Copyright 2015 The Rust Project Developers. See the COPYRIGHT
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; file at the top-level directory of this distribution and at
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; http://rust-lang.org/COPYRIGHT.
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;
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; Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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; http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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; <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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; option. This file may not be copied, modified, or distributed
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; except according to those terms.
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; For more comments about what's going on here see rust_try_msvc_64.ll. The only
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; difference between that and this file is the personality function used as it's
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; different for 32-bit MSVC than it is for 64-bit.
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define i8* @rust_try(void (i8*)* %f, i8* %env)
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personality i8* bitcast (i32 (...)* @_except_handler3 to i8*)
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{
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invoke void %f(i8* %env)
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to label %normal
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unwind label %catch
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normal:
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ret i8* null
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catch:
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%vals = landingpad { i8*, i32 }
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catch i8* bitcast (i32 (i8*, i8*)* @__rust_try_filter to i8*)
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%ehptr = extractvalue { i8*, i32 } %vals, 0
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%sel = extractvalue { i8*, i32 } %vals, 1
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%filter_sel = call i32 @llvm.eh.typeid.for(i8* bitcast (i32 (i8*, i8*)* @__rust_try_filter to i8*))
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%is_filter = icmp eq i32 %sel, %filter_sel
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br i1 %is_filter, label %catch-return, label %catch-resume
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catch-return:
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ret i8* %ehptr
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catch-resume:
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resume { i8*, i32 } %vals
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}
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declare i32 @_except_handler3(...)
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declare i32 @__rust_try_filter(i8*, i8*)
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declare i32 @llvm.eh.typeid.for(i8*) readnone nounwind

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