[WebAssembly] Fix handling of COPY instructions in WebAssemblyRegStackify.

[oota-llvm.git] / lib / Target / WebAssembly / WebAssemblyCFGStackify.cpp

diff --git a/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp b/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
index 6ac53662359db1b52186c96514a9c900cd41c46b..e9671ee07e69c668e717844c4df8d01848b6dbcc 100644 (file)
--- a/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
+++ b/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
@@ -320,11 +320,12 @@ static void PlaceBlockMarker(MachineBasicBlock &MBB, MachineFunction &MF,
     // the BLOCK needs to be above the LOOP.
     InsertPos = Header->begin();
   } else {
-    // Otherwise, insert the BLOCK as late in Header as we can, but before any
-    // existing BLOCKs.
+    // Otherwise, insert the BLOCK as late in Header as we can, but before the
+    // beginning of the local expression tree and any nested BLOCKs.
     InsertPos = Header->getFirstTerminator();
     while (InsertPos != Header->begin() &&
-           prev(InsertPos)->getOpcode() == WebAssembly::BLOCK)
+           prev(InsertPos)->definesRegister(WebAssembly::EXPR_STACK) &&
+           prev(InsertPos)->getOpcode() != WebAssembly::LOOP)
       --InsertPos;
   }