[WebAssembly] Implement eliminateCallFramePseudo

Summary:
Implement eliminateCallFramePsuedo to handle ADJCALLSTACKUP/DOWN
pseudo-instructions. Add a test calling a vararg function which causes non-0
adjustments. This revealed an issue with RegisterCoalescer wherein it
eliminates a COPY from SP32 to a vreg but failes to update the live ranges
of EXPR_STACK, causing a machineinstr verifier failure (so this test
is commented out).

Also add a dynamic alloca test, which causes a callseq_end dag node with
a 0 (instead of undef) second argument to be generated. We currently fail to
select that, so adjust the ADJCALLSTACKUP tablegen code to handle it.

Differential Revision: http://reviews.llvm.org/D15587

llvm-svn: 255844

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
index dcc393db6ea..c33c21fe685 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
@@ -169,6 +169,9 @@ void WebAssemblyPassConfig::addPreRegAlloc() {
 
   // Mark registers as representing wasm's expression stack.
   addPass(createWebAssemblyRegStackify());
+  // The register coalescing pass has a bad interaction with COPY MIs which have
+  // EXPR_STACK as an extra operand
+  //disablePass(&RegisterCoalescerID);
 }
 
 void WebAssemblyPassConfig::addPostRegAlloc() {