add options no-tail-merge and enable-tail-merge

Author: optimisan

llvm/include/llvm/Passes/MachinePassRegistry.def

@@ -195,16 +195,11 @@ MACHINE_FUNCTION_PASS("verify<machine-trace-metrics>", MachineTraceMetricsVerifi
 
 MACHINE_FUNCTION_PASS_WITH_PARAMS(
     "block-placement", "MachineBlockPlacementPass",
-    [](bool NoTailMerge) {
-      // Tail merging is enabled by default, so this option
-      // is to disable it.
-      return MachineBlockPlacementPass(!NoTailMerge);
+    [](bool AllowTailMerge) {
+      // Default is true.
+      return MachineBlockPlacementPass(AllowTailMerge);
     },
-    [](StringRef Params) {
-      return parseSinglePassOption(Params, "no-tail-merge",
-                                   "MachineBlockPlacementPass");
-    },
-    "no-tail-merge")
+    parseMachineBlockPlacementPassOptions, "no-tail-merge;enable-tail-merge")
 
 MACHINE_FUNCTION_PASS_WITH_PARAMS(
     "machine-sink", "MachineSinkingPass",

llvm/lib/Passes/PassBuilder.cpp

@@ -1439,6 +1439,19 @@ Expected<bool> parseMachineSinkingPassOptions(StringRef Params) {
                                             "MachineSinkingPass");
 }
 
+Expected<bool> parseMachineBlockPlacementPassOptions(StringRef Params) {
+  bool AllowTailMerge = true;
+  if (Params == "no-tail-merge")
+    AllowTailMerge = false;
+  else if (!Params.empty() && Params != "enable-tail-merge")
+    return make_error<StringError>(
+        formatv("invalid MachineBlockPlacementPass parameter '{0}' ", Params)
+            .str(),
+        inconvertibleErrorCode());
+
+  return AllowTailMerge;
+}
+
 } // namespace
 
 /// Tests whether a pass name starts with a valid prefix for a default pipeline

llvm/test/CodeGen/AMDGPU/loop_header_nopred.mir

@@ -2,7 +2,7 @@
 # RUN: llc -mtriple=amdgcn -o - -run-pass=block-placement -mcpu=gfx1010 -mattr=-inst-fwd-prefetch-bug -verify-machineinstrs %s | FileCheck -check-prefixes=GFX10 %s
 # RUN: llc -mtriple=amdgcn -o - -run-pass=block-placement -mcpu=gfx1100 -mattr=-inst-fwd-prefetch-bug -verify-machineinstrs %s | FileCheck -check-prefixes=GFX11 %s
 
-# RUN: llc -mtriple=amdgcn -o - -passes='require<profile-summary>,function(machine-function(block-placement))' -mcpu=gfx1100 -mattr=-inst-fwd-prefetch-bug -verify-machineinstrs %s | FileCheck -check-prefixes=GFX11 %s
+# RUN: llc -mtriple=amdgcn -o - -passes='require<profile-summary>,function(machine-function(block-placement<enable-tail-merge>))' -mcpu=gfx1100 -mattr=-inst-fwd-prefetch-bug -verify-machineinstrs %s | FileCheck -check-prefixes=GFX11 %s
 
 # Used to fail with
 # Assertion `Out && "Header of loop has no predecessors from outside loop?"