From 9948fe6997bc59e0fbf3535404013784f5cb183d Mon Sep 17 00:00:00 2001
From: James Molloy <jmolloy@google.com>
Date: Wed, 9 Oct 2019 09:15:34 +0000
Subject: [PATCH] [TableGen] Fix crash when using HwModes in CodeEmitterGen

When an instruction has an encoding definition for only a subset of
the available HwModes, ensure we just avoid generating an encoding
rather than crash.

llvm-svn: 374150
---
 llvm/test/TableGen/HwModeEncodeDecode.td | 9 +++++++++
 llvm/utils/TableGen/CodeEmitterGen.cpp   | 3 ++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/llvm/test/TableGen/HwModeEncodeDecode.td b/llvm/test/TableGen/HwModeEncodeDecode.td
index b76d856..1c9b86ff 100644
--- a/llvm/test/TableGen/HwModeEncodeDecode.td
+++ b/llvm/test/TableGen/HwModeEncodeDecode.td
@@ -56,6 +56,15 @@ def bar: Instruction {
   let Inst{1-0} = 0b10;
   let AsmString = "bar  $factor";
 }
+
+def baz : Instruction {
+  let InOperandList = (ins i32imm:$factor);
+  bits<32> Inst;
+  let EncodingInfos = EncodingByHwMode<
+    [ModeB], [fooTypeEncA]
+  >;
+  let AsmString = "foo  $factor";
+}
 }
 
 // DECODER-LABEL: DecoderTable_ModeA32[] =
diff --git a/llvm/utils/TableGen/CodeEmitterGen.cpp b/llvm/utils/TableGen/CodeEmitterGen.cpp
index b021d08..42f69cb 100644
--- a/llvm/utils/TableGen/CodeEmitterGen.cpp
+++ b/llvm/utils/TableGen/CodeEmitterGen.cpp
@@ -367,7 +367,8 @@ void CodeEmitterGen::emitInstructionBaseValues(
     if (const RecordVal *RV = R->getValue("EncodingInfos")) {
       if (auto *DI = dyn_cast_or_null<DefInit>(RV->getValue())) {
         EncodingInfoByHwMode EBM(DI->getDef(), HWM);
-        EncodingDef = EBM.get(HwMode);
+        if (EBM.hasMode(HwMode))
+          EncodingDef = EBM.get(HwMode);
       }
     }
     BitsInit *BI = EncodingDef->getValueAsBitsInit("Inst");
-- 
2.7.4