[llvm] r267943 - [PowerPC] Fix the EH_SjLj_Setup pseudo.

[Marcin Koscielnicki via llvm-commits]

Author: koriakin
Date: Thu Apr 28 16:24:37 2016
New Revision: 267943

URL: http://llvm.org/viewvc/llvm-project?rev=267943&view=rev
Log:
[PowerPC] Fix the EH_SjLj_Setup pseudo.

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.

Added:
    llvm/trunk/test/CodeGen/PowerPC/2016-04-28-setjmp.ll
Modified:
    llvm/trunk/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp
    llvm/trunk/lib/Target/PowerPC/PPCInstrInfo.td

Modified: llvm/trunk/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp?rev=267943&r1=267942&r2=267943&view=diff
==============================================================================
--- llvm/trunk/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp (original)
+++ llvm/trunk/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp Thu Apr 28 16:24:37 2016
@@ -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);

Modified: llvm/trunk/lib/Target/PowerPC/PPCInstrInfo.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCInstrInfo.td?rev=267943&r1=267942&r2=267943&view=diff
==============================================================================
--- llvm/trunk/lib/Target/PowerPC/PPCInstrInfo.td (original)
+++ llvm/trunk/lib/Target/PowerPC/PPCInstrInfo.td Thu Apr 28 16:24:37 2016
@@ -1397,7 +1397,10 @@ let hasSideEffects = 1, isBarrier = 1, u
                           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", []>;
 }

Added: llvm/trunk/test/CodeGen/PowerPC/2016-04-28-setjmp.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/PowerPC/2016-04-28-setjmp.ll?rev=267943&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/PowerPC/2016-04-28-setjmp.ll (added)
+++ llvm/trunk/test/CodeGen/PowerPC/2016-04-28-setjmp.ll Thu Apr 28 16:24:37 2016
@@ -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"
+
+ at 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()