[llvm] bd6c16c - [MachineOutliner] Avoid ranges that cross bundle boundary (#148977)

[via llvm-commits]

Author: Ellis Hoag
Date: 2025-07-16T09:51:25-07:00
New Revision: bd6c16c6cfe28105d992fa997dce6e18ea86a5a4

URL: https://github.com/llvm/llvm-project/commit/bd6c16c6cfe28105d992fa997dce6e18ea86a5a4
DIFF: https://github.com/llvm/llvm-project/commit/bd6c16c6cfe28105d992fa997dce6e18ea86a5a4.diff

LOG: [MachineOutliner] Avoid ranges that cross bundle boundary (#148977)

We found some code that was hitting this assert because
`getOutlinableRanges()` was trying to create a range that crossed a
bundle boundary.


https://github.com/llvm/llvm-project/blob/ae3bba4d15a10646ea91c6c0795633b82939857b/llvm/include/llvm/CodeGen/MachineInstrBundleIterator.h#L133-L135

Avoid creating those ranges and add a test that hit the assert.

Added: 
    

Modified: 
    llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
    llvm/test/CodeGen/AArch64/machine-outliner-safe-range-in-middle.mir

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
index cdb224d0cd09f..996b0edd24200 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -9585,10 +9585,15 @@ AArch64InstrInfo::getOutlinableRanges(MachineBasicBlock &MBB,
       };
   auto SaveRangeIfNonEmpty = [&RangeLen, &Ranges, &RangeBegin, &RangeEnd]() {
     // At least one unsafe register is not dead. We do not want to outline at
-    // this point. If it is long enough to outline from, save the range
-    // [RangeBegin, RangeEnd).
-    if (RangeLen > 1)
-      Ranges.push_back(std::make_pair(RangeBegin, RangeEnd));
+    // this point. If it is long enough to outline from and does not cross a
+    // bundle boundary, save the range [RangeBegin, RangeEnd).
+    if (RangeLen <= 1)
+      return;
+    if (!RangeBegin.isEnd() && RangeBegin->isBundledWithPred())
+      return;
+    if (!RangeEnd.isEnd() && RangeEnd->isBundledWithPred())
+      return;
+    Ranges.emplace_back(RangeBegin, RangeEnd);
   };
   // Find the first point where all unsafe registers are dead.
   // FIND: <safe instr> <-- end of first potential range

diff  --git a/llvm/test/CodeGen/AArch64/machine-outliner-safe-range-in-middle.mir b/llvm/test/CodeGen/AArch64/machine-outliner-safe-range-in-middle.mir
index 23811425101fd..b99ca25a5432d 100644
--- a/llvm/test/CodeGen/AArch64/machine-outliner-safe-range-in-middle.mir
+++ b/llvm/test/CodeGen/AArch64/machine-outliner-safe-range-in-middle.mir
@@ -16,27 +16,53 @@ body:             |
     ; CHECK-NEXT: {{  $}}
     ; CHECK-NEXT: BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $x0, implicit-def $x1, implicit-def $x2, implicit-def $x3, implicit-def $x16, implicit $x0, implicit $sp
     ; CHECK-NEXT: $x9 = ADDXri $x16, 16, 0
-    ; CHECK-NEXT: $x16 = ADDXri killed $x16, 16, 0
+    ; CHECK-NEXT: $x16 = ADDXri killed $x16, 16, 1
     ; CHECK-NEXT: BL @OUTLINED_FUNCTION_0, implicit-def $lr, implicit $sp, implicit-def $lr, implicit-def $x0, implicit-def $x1, implicit-def $x2, implicit-def $x3, implicit-def $x16, implicit $x0, implicit $sp
     ; CHECK-NEXT: $x9 = ADDXri $x9, 16, 0
-    ; CHECK-NEXT: $x16 = ADDXri killed $x16, 16, 0
+    ; CHECK-NEXT: $x16 = ADDXri killed $x16, 16, 2
     ; CHECK-NEXT: RET undef $x9
     $x0 = ADDXri $x0, 0, 0
     $x1 = ADDXri $x0, 1, 0
     $x2 = ADDXri $x0, 2, 0
     $x3 = ADDXri $x0, 3, 0
-
-    ; End safe range
     $x16 = ADDXri $x0, 16, 0
     $x9 = ADDXri $x16, 16, 0
-    $x16 = ADDXri killed $x16, 16, 0
-
+    $x16 = ADDXri killed $x16, 16, 1
+    ; End safe range
     $x0 = ADDXri $x0, 0, 0
     $x1 = ADDXri $x0, 1, 0
     $x2 = ADDXri $x0, 2, 0
     $x3 = ADDXri $x0, 3, 0
-    ; End safe range
     $x16 = ADDXri $x0, 16, 0
     $x9 = ADDXri $x9, 16, 0
-    $x16 = ADDXri killed $x16, 16, 0
+    $x16 = ADDXri killed $x16, 16, 2
+    ; End safe range
     RET undef $x9
+...
+---
+name:           unsafe_range_bundle
+tracksRegLiveness: true
+machineFunctionInfo:
+  hasRedZone:      false
+body:             |
+  bb.0:
+    liveins: $x0
+    ; CHECK-LABEL: name: unsafe_range_bundle
+    ; CHECK: liveins: $x0
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: $x0 = ADDXri $x0, 0, 0
+    ; CHECK-NEXT: $x16 = ADDXri $x0, 16, 0
+    ; CHECK-NEXT: BUNDLE {
+    ; CHECK-NEXT:   $x16 = ADDXri killed $x16, 16, 3
+    ; CHECK-NEXT:   $x1 = ADDXri $x0, 0, 0
+    ; CHECK-NEXT: }
+    ; CHECK-NEXT: RET undef $x9
+    $x0 = ADDXri $x0, 0, 0
+    $x16 = ADDXri $x0, 16, 0
+    BUNDLE { ; Bundle crosses a safe range
+      $x16 = ADDXri killed $x16, 16, 3
+      ; End safe range
+      $x1 = ADDXri $x0, 0, 0
+    }
+    RET undef $x9
+...