Doomhowl-Interactive/llvm-project
0
0
Fork 0
Code Issues Pull Requests Actions 5 Packages Projects Releases Wiki Activity

[mlir] Fix crash in dropRedundantArguments with produced operands. (#172759)

Browse Source 
dropRedundantArguments was incorrectly indexing into forwardedOperands
using the block argument index directly. This crashes when the block has
produced operands (generated by the terminator, not forwarded from
predecessors) because forwardedOperands doesn't include them.

The fix checks isOperandProduced() to skip produced arguments and uses
SuccessorOperands::operator[] which handles the offset correctly.
This commit is contained in:
Ben Vanik
2026-01-06 22:53:28 -08:00
committed by GitHub
parent 16be2c0555
commit 4ac6431755
2 changed files with 46 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
mlir/lib/Transforms/Utils/RegionUtils.cpp
View File

@@ -975,12 +975,22 @@ static LogicalResult dropRedundantArguments(RewriterBase &rewriter,
}
unsigned succIndex = predIt.getSuccessorIndex();
SuccessorOperands succOperands = branch.getSuccessorOperands(succIndex);
auto branchOperands = succOperands.getForwardedOperands();
// Produced operands are generated by the terminator operation itself
// (e.g., results of an async call) and cannot be forwarded or dropped.
if (succOperands.isOperandProduced(argIdx)) {
sameArg = false;
break;
}
// Get the forwarded operand value using operator[] which correctly
// adjusts for the produced operand offset.
Value operandValue = succOperands[argIdx];
if (!commonValue) {
commonValue = branchOperands[argIdx];
commonValue = operandValue;
continue;
}
if (branchOperands[argIdx] != commonValue) {
if (operandValue != commonValue) {
sameArg = false;
break;
}

33
mlir/test/Transforms/canonicalize-block-merge.mlir
View File

@@ -318,3 +318,36 @@ func.func @nested_loop(%arg0: i32, %arg1: i32, %arg2: i32, %arg3: i32, %arg4: i3
^EXIT: // pred: ^Loop_header
return
}
// Test that dropRedundantArguments correctly handles produced successor operands.
// CHECK-LABEL: func.func @produced_operand_not_dropped
// CHECK-SAME: (%{{.*}}: i1) -> i32 {
func.func @produced_operand_not_dropped(%cond: i1) -> i32 {
// CHECK-DAG: %[[C42:.*]] = arith.constant 42 : i32
%c42 = arith.constant 42 : i32
// CHECK: "test.internal_br"()[^[[UNUSED:.*]], ^[[TARGET:.*]]]
cf.cond_br %cond, ^bb1, ^bb2
^bb1:
// Branches via error path (successor 1) which has 1 produced + 1 forwarded arg.
"test.internal_br"(%c42) [^bb_unused, ^bb_target] {
operandSegmentSizes = array<i32: 0, 1>
} : (i32) -> ()
^bb2:
// Also branches via error path with the same forwarded value.
"test.internal_br"(%c42) [^bb_unused, ^bb_target] {
operandSegmentSizes = array<i32: 0, 1>
} : (i32) -> ()
// CHECK: ^[[UNUSED]]:
^bb_unused:
// CHECK: "test.terminator"
"test.terminator"() : () -> ()
// arg0: produced by test.internal_br (kept)
// arg1: forwarded %c42 (dropped - same from both preds, replaced with %c42 directly)
// CHECK: ^[[TARGET]](%[[PRODUCED:.*]]: i32):
^bb_target(%arg0: i32, %arg1: i32):
// CHECK: %[[RESULT:.*]] = arith.addi %[[PRODUCED]], %[[C42]] : i32
%result = arith.addi %arg0, %arg1 : i32
// CHECK: return %[[RESULT]] : i32
return %result : i32
}