[PATCH] D50639: Change how finalizeBundle selects debug location for the BUNDLE instruction

[Bjorn Pettersson via Phabricator via llvm-commits]

bjope created this revision.

Previously a BUNDLE instruction inherited the DebugLoc from the
first instruction in the bundle, even if that DebugLoc had no
DILocation. With this commit this is changed into selecting the
first DebugLoc that has a DILocation, by searching among the
bundled instructions.

The idea is to reduce amount of bundles that are lacking
debug locations.


Repository:
  rL LLVM

https://reviews.llvm.org/D50639

Files:
  lib/CodeGen/MachineInstrBundle.cpp
  test/CodeGen/Hexagon/packetize-debug-loc.mir


Index: test/CodeGen/Hexagon/packetize-debug-loc.mir
===================================================================
--- /dev/null
+++ test/CodeGen/Hexagon/packetize-debug-loc.mir
@@ -0,0 +1,58 @@
+# RUN: llc -march=hexagon -run-pass hexagon-packetizer %s -o - | FileCheck %s
+
+##############################################################################
+# This test case is not really hexagon specific, but we use hexagon to get
+# bundling.
+#
+# The goal is to verify that the BUNDLE instruction is getting the first
+# non-empty debug location among the bundled instructions.
+##############################################################################
+
+--- |
+  define void @test() { ret void }
+
+  !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "llvm", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !3, retainedTypes: !3)
+  !1 = distinct !DISubprogram(name: "test", scope: !3, file: !3, line: 1, type: !2, isLocal: false, isDefinition: true, scopeLine: 2, flags: DIFlagPrototyped, isOptimized: true, unit: !0)
+  !2 = !DISubroutineType(types: !3)
+  !3 = !{null}
+  !5 = !DILocation(line: 126, column: 9, scope: !2)
+  !6 = !DILocation(line: 321, column: 4, scope: !2)
+
+...
+---
+name: test
+tracksRegLiveness: true
+body: |
+  bb.0:
+    liveins: $r1
+    $r2 = L2_loadri_io $r1, 0, debug-location !5
+    $r3 = L2_loadri_io $r1, 0, debug-location !6
+
+    $r4 = L2_loadri_io $r1, 0
+    $r5 = L2_loadri_io $r1, 0, debug-location !5
+
+    $r6 = L2_loadri_io $r1, 0, debug-location !6
+    $r7 = L2_loadri_io $r1, 0
+
+    $r8 = L2_loadri_io $r1, 0
+    $r9 = L2_loadri_io $r1, 0
+...
+
+# CHECK-LABEL: name: test
+
+# CHECK: BUNDLE
+# CHECK-SAME: debug-location [[DL1:[0-9x<>]+]]
+# CHECK-NEXT: L2_loadri_io $r1, 0, debug-location [[DL1]]
+# CHECK-NEXT: L2_loadri_io $r1, 0, debug-location [[DL2:[0-9x<>]+]]
+
+# CHECK: BUNDLE
+# CHECK-SAME: debug-location [[DL1]]
+# CHECK-NEXT: L2_loadri_io $r1, 0{{$}}
+# CHECK-NEXT: L2_loadri_io $r1, 0, debug-location [[DL1]]
+
+# CHECK: BUNDLE
+# CHECK-SAME: debug-location [[DL2]]
+# CHECK-NEXT: L2_loadri_io $r1, 0, debug-location [[DL2]]
+
+# No debug-location printouts expected for the last bundle
+# CHECK-NOT: debug-location
Index: lib/CodeGen/MachineInstrBundle.cpp
===================================================================
--- lib/CodeGen/MachineInstrBundle.cpp
+++ lib/CodeGen/MachineInstrBundle.cpp
@@ -105,6 +105,16 @@
   return llvm::finalizeBundles(MF);
 }
 
+/// Return the first found DebugLoc that has a DILocation, given a range of
+/// instructions. The search range is from FirstMI to LastMI (exclusive). If no
+/// DILocation is found, then an empty location is returned.
+static DebugLoc getDebugLoc(MachineBasicBlock::instr_iterator FirstMI,
+                            MachineBasicBlock::instr_iterator LastMI) {
+  for (auto MII = FirstMI; MII != LastMI; ++MII)
+    if (MII->getDebugLoc().get())
+      return MII->getDebugLoc();
+  return DebugLoc();
+}
 
 /// finalizeBundle - Finalize a machine instruction bundle which includes
 /// a sequence of instructions starting from FirstMI to LastMI (exclusive).
@@ -123,7 +133,7 @@
   const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
 
   MachineInstrBuilder MIB =
-      BuildMI(MF, FirstMI->getDebugLoc(), TII->get(TargetOpcode::BUNDLE));
+      BuildMI(MF, getDebugLoc(FirstMI, LastMI), TII->get(TargetOpcode::BUNDLE));
   Bundle.prepend(MIB);
 
   SmallVector<unsigned, 32> LocalDefs;


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