[RISCV] Fix incorrect use of MCInstBuilder

This is a fix for r339314.

MCInstBuilder uses the named parameter idiom and an 'operator MCInst&' to ease
the creation of MCInsts. As the object of MCInstBuilder owns the MCInst is
manipulating, the lifetime of the MCInst is bound to that of MCInstBuilder.

In r339314 I bound a reference to the MCInst in an initializer. The
temporary of MCInstBuilder (and also its MCInst) is destroyed at the end of
the declaration leading to a dangling reference.

Fix this by using MCInstBuilder inside an argument of a function call.
Temporaries in function calls are destroyed in the enclosing full expression,
so the the reference to MCInst is still valid when emitToStreamer executes.

llvm-svn: 339654

1 files changed, 6 insertions, 8 deletions

diff --git a/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp b/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
index 5a56ddf0656..3a5257206bf 100644
--- a/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
+++ b/llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp
@@ -1227,19 +1227,17 @@ void RISCVAsmParser::emitLoadLocalAddress(MCInst &Inst, SMLoc IDLoc,
   const RISCVMCExpr *Symbol = RISCVMCExpr::create(
       Inst.getOperand(1).getExpr(), RISCVMCExpr::VK_RISCV_PCREL_HI, Ctx);
 
-  MCInst &AUIPC =
-      MCInstBuilder(RISCV::AUIPC).addOperand(DestReg).addExpr(Symbol);
-  emitToStreamer(Out, AUIPC);
+  emitToStreamer(
+      Out, MCInstBuilder(RISCV::AUIPC).addOperand(DestReg).addExpr(Symbol));
 
   const MCExpr *RefToLinkTmpLabel =
       RISCVMCExpr::create(MCSymbolRefExpr::create(TmpLabel, Ctx),
                           RISCVMCExpr::VK_RISCV_PCREL_LO, Ctx);
 
-  MCInst &ADDI = MCInstBuilder(RISCV::ADDI)
-                     .addOperand(DestReg)
-                     .addOperand(DestReg)
-                     .addExpr(RefToLinkTmpLabel);
-  emitToStreamer(Out, ADDI);
+  emitToStreamer(Out, MCInstBuilder(RISCV::ADDI)
+                          .addOperand(DestReg)
+                          .addOperand(DestReg)
+                          .addExpr(RefToLinkTmpLabel));
 }
 
 bool RISCVAsmParser::processInstruction(MCInst &Inst, SMLoc IDLoc,