[llvm] 4561352 - [CodeEmitter] Fix encoding wide instructions on big-endian hosts

[Jay Foad via llvm-commits]

Author: Jay Foad
Date: 2022-06-07T19:06:28+01:00
New Revision: 4561352f7bd972939f19d7ff8462386c97b584ad

URL: https://github.com/llvm/llvm-project/commit/4561352f7bd972939f19d7ff8462386c97b584ad
DIFF: https://github.com/llvm/llvm-project/commit/4561352f7bd972939f19d7ff8462386c97b584ad.diff

LOG: [CodeEmitter] Fix encoding wide instructions on big-endian hosts

For instructions wider than 64 bits the InstBits table is initialized in
64-bit chunks from APInt::getRawData, but it was being read with
LoadIntFromMemory which is byte-based.

Fix this by reading the table with the APInt constructor that takes an
ArrayRef to the raw data instead.

This is currently NFC for in-tree targets but fixes AMDGPU failures on
big-endian hosts that were caused by D126483 until it was reverted.

Differential Revision: https://reviews.llvm.org/D127195

Added: 
    

Modified: 
    llvm/utils/TableGen/CodeEmitterGen.cpp

Removed: 
    


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diff  --git a/llvm/utils/TableGen/CodeEmitterGen.cpp b/llvm/utils/TableGen/CodeEmitterGen.cpp
index f446e5fe44148..8f96b7ffc279e 100644
--- a/llvm/utils/TableGen/CodeEmitterGen.cpp
+++ b/llvm/utils/TableGen/CodeEmitterGen.cpp
@@ -482,14 +482,12 @@ void CodeEmitterGen::run(raw_ostream &o) {
     // Emit initial function code
     if (UseAPInt) {
       int NumWords = APInt::getNumWords(BitWidth);
-      int NumBytes = (BitWidth + 7) / 8;
       o << "  const unsigned opcode = MI.getOpcode();\n"
-        << "  if (Inst.getBitWidth() != " << BitWidth << ")\n"
-        << "    Inst = Inst.zext(" << BitWidth << ");\n"
         << "  if (Scratch.getBitWidth() != " << BitWidth << ")\n"
         << "    Scratch = Scratch.zext(" << BitWidth << ");\n"
-        << "  LoadIntFromMemory(Inst, (const uint8_t *)&InstBits[opcode * "
-        << NumWords << "], " << NumBytes << ");\n"
+        << "  Inst = APInt(" << BitWidth
+        << ", makeArrayRef(InstBits + opcode * " << NumWords << ", " << NumWords
+        << "));\n"
         << "  APInt &Value = Inst;\n"
         << "  APInt &op = Scratch;\n"
         << "  switch (opcode) {\n";