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[PowerPC] Fix the EH_SjLj_Setup pseudo.

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This instruction is just a control flow marker - it should not
actually exist in the object file.  Unfortunately, nothing catches
it before it gets to AsmPrinter.  If integrated assembler is used,
it's considered to be a normal 4-byte instruction, and emitted as
an all-0 word, crashing the program.  With external assembler,
a comment is emitted.

Fixed by setting Size to 0 and handling it in MCCodeEmitter - this
means the comment will still be emitted if integrated assembler
is not used.

This broke an ASan test, which has been disabled for a long time
as a result (see the discussion on D19657).  We can reenable it
once this lands.

llvm-svn: 267943
This commit is contained in:
Marcin Koscielnicki 2016-04-28 21:24:37 +00:00
parent 211d6a827a
commit 832d560a7e
3 changed files with 54 additions and 1 deletions
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2
lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp
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@ -113,6 +113,8 @@ public:
// Output the constant in big/little endian byte order.
unsigned Size = Desc.getSize();
switch (Size) {
case 0:
break;
case 4:
if (IsLittleEndian) {
support::endian::Writer<support::little>(OS).write<uint32_t>(Bits);

5
lib/Target/PowerPC/PPCInstrInfo.td
View File

@ -1397,7 +1397,10 @@ let hasSideEffects = 1, isBarrier = 1, usesCustomInserter = 1 in {
Requires<[In32BitMode]>;
}
let isBranch = 1, isTerminator = 1 in {
// This pseudo is never removed from the function, as it serves as
// a terminator. Size is set to 0 to prevent the builtin assembler
// from emitting it.
let isBranch = 1, isTerminator = 1, Size = 0 in {
def EH_SjLj_Setup : Pseudo<(outs), (ins directbrtarget:$dst),
"#EH_SjLj_Setup\t$dst", []>;
}

48
test/CodeGen/PowerPC/2016-04-28-setjmp.ll Normal file
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@ -0,0 +1,48 @@
; RUN: llc -filetype=obj <%s | llvm-objdump --disassemble - | FileCheck %s
target datalayout = "e-m:e-i64:64-n32:64"
target triple = "powerpc64le-unknown-linux-gnu"
@ptr = common global i8* null, align 8
; Verify there's no junk between these two instructions from misemitted
; EH_SjLj_Setup.
; CHECK: li 3, 1
; CHECK-NEXT: b .+4
define void @h() nounwind {
%1 = load i8**, i8*** bitcast (i8** @ptr to i8***), align 8
%2 = tail call i8* @llvm.frameaddress(i32 0)
store i8* %2, i8** %1, align 8
%3 = tail call i8* @llvm.stacksave()
%4 = getelementptr inbounds i8*, i8** %1, i64 2
store i8* %3, i8** %4, align 8
%5 = bitcast i8** %1 to i8*
%6 = tail call i32 @llvm.eh.sjlj.setjmp(i8* %5)
%7 = icmp eq i32 %6, 0
br i1 %7, label %9, label %8
; <label>:8: ; preds = %0
tail call void @g()
br label %10
; <label>:9: ; preds = %0
tail call void @f()
br label %10
; <label>:10: ; preds = %9, %8
ret void
}
; Function Attrs: nounwind readnone
declare i8* @llvm.frameaddress(i32)
; Function Attrs: nounwind
declare i8* @llvm.stacksave()
; Function Attrs: nounwind
declare i32 @llvm.eh.sjlj.setjmp(i8*)
declare void @g()
declare void @f()