DEBUG_COUNTER(VisitCounter, "instcombine-visit",
"Controls which instructions are visited");
-static constexpr unsigned InstCombineDefaultMaxIterations = UINT_MAX - 1;
+static constexpr unsigned InstCombineDefaultMaxIterations = 1000;
+static constexpr unsigned InstCombineDefaultInfiniteLoopThreshold = 1000;
static cl::opt<bool>
EnableCodeSinking("instcombine-code-sinking", cl::desc("Enable code sinking"),
cl::desc("Limit the maximum number of instruction combining iterations"),
cl::init(InstCombineDefaultMaxIterations));
+static cl::opt<unsigned> InfiniteLoopDetectionThreshold(
+ "instcombine-infinite-loop-threshold",
+ cl::desc("Number of instruction combining iterations considered an "
+ "infinite loop"),
+ cl::init(InstCombineDefaultInfiniteLoopThreshold), cl::Hidden);
+
static cl::opt<unsigned>
MaxArraySize("instcombine-maxarray-size", cl::init(1024),
cl::desc("Maximum array size considered when doing a combine"));
unsigned Iteration = 0;
while (true) {
++Iteration;
+
+ if (Iteration > InfiniteLoopDetectionThreshold) {
+ report_fatal_error(
+ "Instruction Combining seems stuck in an infinite loop after " +
+ Twine(InfiniteLoopDetectionThreshold) + " iterations.");
+ }
+
if (Iteration > MaxIterations) {
LLVM_DEBUG(dbgs() << "\n\n[IC] Iteration limit #" << MaxIterations
<< " on " << F.getName()
<< " reached; stopping before reaching a fixpoint\n");
- LLVM_DEBUG(dbgs().flush());
- assert(Iteration <= InstCombineDefaultMaxIterations &&
- "InstCombine stuck in an infinite loop?");
break;
}
; RUN: opt < %s -instcombine --instcombine-max-iterations=0 -S | FileCheck %s --check-prefix=ZERO
; RUN: opt < %s -instcombine --instcombine-max-iterations=1 -S | FileCheck %s --check-prefix=ONE
; RUN: opt < %s -instcombine -S | FileCheck %s --check-prefix=FIXPOINT
+; RUN: not opt < %s -instcombine -S --instcombine-infinite-loop-threshold=3 2>&1 | FileCheck %s --check-prefix=LOOP
; Based on xor-of-icmps-with-extra-uses.ll. This requires multiple iterations of
; InstCombine to reach a fixpoint.
; FIXPOINT-NEXT: [[TMP1:%.*]] = icmp ult i32 [[X_OFF]], 65535
; FIXPOINT-NEXT: ret i1 [[TMP1]]
+; LOOP: LLVM ERROR: Instruction Combining seems stuck in an infinite loop after 3 iterations.
+
%cond0 = icmp sgt i32 %X, 32767
%cond1 = icmp sgt i32 %X, -32768
%select = select i1 %cond0, i32 32767, i32 -32768