[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.

llvm-svn: 267943

2 files changed, 6 insertions, 1 deletions

diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp
index 0f6385e0a67..e7b2d8369f2 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp
@@ -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);
diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.td b/llvm/lib/Target/PowerPC/PPCInstrInfo.td
index 32558d35513..838889660a3 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.td
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.td
@@ -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", []>;
 }