[mips] Emit the .insn directive for empty basic blocks.

Summary:
In microMIPS, labels need to know whether they are on code or data. This is
indicated with STO_MIPS_MICROMIPS and can be inferred by being followed
by instructions. For empty basic blocks, we can ensure this by emitting the
.insn directive after the label.

Also, this fixes some failures in our out-of-tree microMIPS buildbots, for the
exception handling regression tests under: SingleSource/Regression/C++/EH

Reviewers: dsanders

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9530

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236815 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/Mips/MipsAsmPrinter.cpp b/lib/Target/Mips/MipsAsmPrinter.cpp
index de15e6371d10715897ca2412b757b4c9f0130a6f..9d969330e5bfc732b706c2361a52a842816ae991 100644 (file)
--- a/lib/Target/Mips/MipsAsmPrinter.cpp
+++ b/lib/Target/Mips/MipsAsmPrinter.cpp
@@ -384,6 +384,12 @@ void MipsAsmPrinter::EmitFunctionBodyEnd() {
   OutStreamer->EmitDataRegion(MCDR_DataRegionEnd);
 }
 
+void MipsAsmPrinter::EmitBasicBlockEnd(const MachineBasicBlock &MBB) {
+  MipsTargetStreamer &TS = getTargetStreamer();
+  if (MBB.size() == 0)
+    TS.emitDirectiveInsn();
+}
+
 /// isBlockOnlyReachableByFallthough - Return true if the basic block has
 /// exactly one predecessor and the control transfer mechanism between
 /// the predecessor and this block is a fall-through.

diff --git a/lib/Target/Mips/MipsAsmPrinter.h b/lib/Target/Mips/MipsAsmPrinter.h
index d4c5b8099606a92b0c44bee43cd1a3b984ad2a4f..a7f3304a3da8a7920e357ab7571e4a04b22c22ae 100644 (file)
--- a/lib/Target/Mips/MipsAsmPrinter.h
+++ b/lib/Target/Mips/MipsAsmPrinter.h
@@ -124,6 +124,7 @@ public:
   void EmitFunctionEntryLabel() override;
   void EmitFunctionBodyStart() override;
   void EmitFunctionBodyEnd() override;
+  void EmitBasicBlockEnd(const MachineBasicBlock &MBB) override;
   bool isBlockOnlyReachableByFallthrough(
                                    const MachineBasicBlock* MBB) const override;
   bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,

diff --git a/test/CodeGen/Mips/insn-zero-size-bb.ll b/test/CodeGen/Mips/insn-zero-size-bb.ll
new file mode 100644 (file)
index 0000000..9739c6f
--- /dev/null
+++ b/test/CodeGen/Mips/insn-zero-size-bb.ll
@@ -0,0 +1,27 @@
+; RUN: llc < %s -march=mips -mcpu=mips32 | FileCheck %s
+; RUN: llc < %s -march=mips -mcpu=mips32r3 -mattr=+micromips | FileCheck %s
+; RUN: llc < %s -march=mips -mcpu=mips16 | FileCheck %s
+
+; Verify that we emit the .insn directive for zero-sized (empty) basic blocks.
+; This only really matters for microMIPS and MIPS16.
+
+declare i32 @foo(...)
+declare void @bar()
+
+define void @main() {
+entry:
+  invoke void @bar() #0
+          to label %unreachable unwind label %return
+
+unreachable:
+; CHECK:          ${{.*}}: # %unreachable
+; CHECK-NEXT:         .insn
+  unreachable
+
+return:
+  %0 = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @foo to i8*)
+          catch i8* null
+  ret void
+}
+
+attributes #0 = { noreturn }