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, 8 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Utils/InlineFunction.cpp b/llvm/lib/Transforms/Utils/InlineFunction.cpp
index 9015b36fa35..7443a7f9c5e 100644
--- a/llvm/lib/Transforms/Utils/InlineFunction.cpp
+++ b/llvm/lib/Transforms/Utils/InlineFunction.cpp
@@ -1504,6 +1504,10 @@ llvm::InlineResult llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
   assert(TheCall->getParent() && TheCall->getFunction()
          && "Instruction not in function!");
 
+  // FIXME: we don't inline callbr yet.
+  if (isa<CallBrInst>(TheCall))
+    return false;
+
   // If IFI has any state in it, zap it before we fill it in.
   IFI.reset();
 
@@ -1729,6 +1733,8 @@ llvm::InlineResult llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
         Instruction *NewI = nullptr;
         if (isa<CallInst>(I))
           NewI = CallInst::Create(cast<CallInst>(I), OpDefs, I);
+        else if (isa<CallBrInst>(I))
+          NewI = CallBrInst::Create(cast<CallBrInst>(I), OpDefs, I);
         else
           NewI = InvokeInst::Create(cast<InvokeInst>(I), OpDefs, I);
 
@@ -2031,6 +2037,8 @@ llvm::InlineResult llvm::InlineFunction(CallSite CS, InlineFunctionInfo &IFI,
         Instruction *NewInst;
         if (CS.isCall())
           NewInst = CallInst::Create(cast<CallInst>(I), OpBundles, I);
+        else if (CS.isCallBr())
+          NewInst = CallBrInst::Create(cast<CallBrInst>(I), OpBundles, I);
         else
           NewInst = InvokeInst::Create(cast<InvokeInst>(I), OpBundles, I);
         NewInst->takeName(I);