[llvm] de37da8 - [MachineOutliner] Preserve instruction bundles (#106402)

[via llvm-commits]

Author: Simon Tatham
Date: 2024-09-04T09:06:48+01:00
New Revision: de37da8e37c4c9042563e186068adca98bf59e07

URL: https://github.com/llvm/llvm-project/commit/de37da8e37c4c9042563e186068adca98bf59e07
DIFF: https://github.com/llvm/llvm-project/commit/de37da8e37c4c9042563e186068adca98bf59e07.diff

LOG: [MachineOutliner] Preserve instruction bundles (#106402)

When the machine outliner copies instructions from a source function
into an outlined function, it was doing it using `CloneMachineInstr`,
which is documented as not preserving the interior of any instruction
bundle. So outlining code that includes an instruction bundle would
fail, because in the outlined version, the bundle would be empty, so
instructions would go missing in the move.

This occurs when any bundled instruction appears in the outlined code,
so there was no need to construct an unusual test case: I've just copied
a function from the existing `stp-opt-with-renaming.mir`, which happens
to contain an SVE instruction bundle. Including two identical copies of
that function makes the outliner merge them, and then we check that it
didn't destroy the interior of the bundle in the process.

Added: 
    llvm/test/CodeGen/AArch64/machine-outliner-bundle.mir

Modified: 
    llvm/lib/CodeGen/MachineOutliner.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/CodeGen/MachineOutliner.cpp b/llvm/lib/CodeGen/MachineOutliner.cpp
index 42f410c277179b..97500d0abebad5 100644
--- a/llvm/lib/CodeGen/MachineOutliner.cpp
+++ b/llvm/lib/CodeGen/MachineOutliner.cpp
@@ -763,10 +763,9 @@ MachineFunction *MachineOutliner::createOutlinedFunction(
       BuildMI(MBB, MBB.end(), DL, TII.get(TargetOpcode::CFI_INSTRUCTION))
           .addCFIIndex(MF.addFrameInst(CFI));
     } else {
-      MachineInstr *NewMI = MF.CloneMachineInstr(&MI);
-      NewMI->dropMemRefs(MF);
-      NewMI->setDebugLoc(DL);
-      MBB.insert(MBB.end(), NewMI);
+      MachineInstr &NewMI = TII.duplicate(MBB, MBB.end(), MI);
+      NewMI.dropMemRefs(MF);
+      NewMI.setDebugLoc(DL);
     }
   }
 

diff  --git a/llvm/test/CodeGen/AArch64/machine-outliner-bundle.mir b/llvm/test/CodeGen/AArch64/machine-outliner-bundle.mir
new file mode 100644
index 00000000000000..1dd5b0811bdfb6
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/machine-outliner-bundle.mir
@@ -0,0 +1,54 @@
+# RUN: llc -mtriple=aarch64 -run-pass=machine-outliner \
+# RUN: -verify-machineinstrs %s -o - | FileCheck %s
+
+# CHECK: name: OUTLINED_FUNCTION_0
+# CHECK-NOT: name:
+# CHECK: BUNDLE implicit-def $z3, implicit-def $q3, implicit-def $d3, implicit-def $s3, implicit-def $h3, implicit-def $b3, implicit $z19, implicit $p0, implicit $z16 {
+# CHECK:     $z3 = MOVPRFX_ZZ $z19
+# CHECK:     $z3 = FMUL_ZPmZ_S renamable $p0, killed $z3, renamable $z16
+# CHECK: }
+
+---
+name:            bundled
+alignment:       4
+tracksRegLiveness: true
+frameInfo:
+  maxAlignment:    1
+  maxCallFrameSize: 0
+machineFunctionInfo:
+  hasRedZone:      false
+body:             |
+  bb.0.entry:
+    liveins: $z3, $z19, $p0, $z16
+    renamable $q0 = LDRQui $sp, 1 :: (load 16)
+    STRSui renamable $s0, $sp, 9, implicit killed $q0 :: (store (s32))
+    BUNDLE implicit-def $z3, implicit-def $q3, implicit-def $d3, implicit-def $s3, implicit-def $h3, implicit-def $b3, implicit $z19, implicit $p0, implicit $z16 {
+      $z3 = MOVPRFX_ZZ $z19
+      $z3 = FMUL_ZPmZ_S renamable $p0, killed $z3, renamable $z16
+    }
+    renamable $q0 = LDRQui $sp, 0 :: (load 16, align 32)
+    STRSui renamable $s0, $sp, 10, implicit killed $q0 :: (store (s32))
+    RET undef $lr
+...
+---
+name:            bundled_clone
+alignment:       4
+tracksRegLiveness: true
+frameInfo:
+  maxAlignment:    1
+  maxCallFrameSize: 0
+machineFunctionInfo:
+  hasRedZone:      false
+body:             |
+  bb.0.entry:
+    liveins: $z3, $z19, $p0, $z16
+    renamable $q0 = LDRQui $sp, 1 :: (load 16)
+    STRSui renamable $s0, $sp, 9, implicit killed $q0 :: (store (s32))
+    BUNDLE implicit-def $z3, implicit-def $q3, implicit-def $d3, implicit-def $s3, implicit-def $h3, implicit-def $b3, implicit $z19, implicit $p0, implicit $z16 {
+      $z3 = MOVPRFX_ZZ $z19
+      $z3 = FMUL_ZPmZ_S renamable $p0, killed $z3, renamable $z16
+    }
+    renamable $q0 = LDRQui $sp, 0 :: (load 16, align 32)
+    STRSui renamable $s0, $sp, 10, implicit killed $q0 :: (store (s32))
+    RET undef $lr
+...