Implementation of asm-goto support in LLVM

This patch accompanies the RFC posted here:
http://lists.llvm.org/pipermail/llvm-dev/2018-October/127239.html

This patch adds a new CallBr IR instruction to support asm-goto
inline assembly like gcc as used by the linux kernel. This
instruction is both a call instruction and a terminator
instruction with multiple successors. Only inline assembly
usage is supported today.

This also adds a new INLINEASM_BR opcode to SelectionDAG and
MachineIR to represent an INLINEASM block that is also
considered a terminator instruction.

There will likely be more bug fixes and optimizations to follow
this, but we felt it had reached a point where we would like to
switch to an incremental development model.

Patch by Craig Topper, Alexander Ivchenko, Mikhail Dvoretckii

Differential Revision: https://reviews.llvm.org/D53765

llvm-svn: 353563

1 files changed, 35 insertions, 0 deletions

diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index f4a539e..a15ad55 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -2777,6 +2777,41 @@ void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
       Vals.push_back(VE.getValueID(CatchSwitch.getUnwindDest()));
     break;
   }
+  case Instruction::CallBr: {
+    const CallBrInst *CBI = cast<CallBrInst>(&I);
+    const Value *Callee = CBI->getCalledValue();
+    FunctionType *FTy = CBI->getFunctionType();
+
+    if (CBI->hasOperandBundles())
+      writeOperandBundles(CBI, InstID);
+
+    Code = bitc::FUNC_CODE_INST_CALLBR;
+
+    Vals.push_back(VE.getAttributeListID(CBI->getAttributes()));
+
+    Vals.push_back(CBI->getCallingConv() << bitc::CALL_CCONV |
+                   1 << bitc::CALL_EXPLICIT_TYPE);
+
+    Vals.push_back(VE.getValueID(CBI->getDefaultDest()));
+    Vals.push_back(CBI->getNumIndirectDests());
+    for (unsigned i = 0, e = CBI->getNumIndirectDests(); i != e; ++i)
+      Vals.push_back(VE.getValueID(CBI->getIndirectDest(i)));
+
+    Vals.push_back(VE.getTypeID(FTy));
+    pushValueAndType(Callee, InstID, Vals);
+
+    // Emit value #'s for the fixed parameters.
+    for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
+      pushValue(I.getOperand(i), InstID, Vals); // fixed param.
+
+    // Emit type/value pairs for varargs params.
+    if (FTy->isVarArg()) {
+      for (unsigned i = FTy->getNumParams(), e = CBI->getNumArgOperands();
+           i != e; ++i)
+        pushValueAndType(I.getOperand(i), InstID, Vals); // vararg
+    }
+    break;
+  }
   case Instruction::Unreachable:
     Code = bitc::FUNC_CODE_INST_UNREACHABLE;
     AbbrevToUse = FUNCTION_INST_UNREACHABLE_ABBREV;