"unroll-force-peel-count", cl::init(0), cl::Hidden,
cl::desc("Force a peel count regardless of profiling information."));
+static cl::opt<bool> DisableAdvancedPeeling(
+ "disable-advanced-peeling", cl::init(false), cl::Hidden,
+ cl::desc(
+ "Disable advance peeling. Issues for convergent targets (D134803)."));
+
static const char *PeeledCountMetaData = "llvm.loop.peeled.count";
// Check whether we are capable of peeling this loop.
bool llvm::canPeel(Loop *L) {
// Make sure the loop is in simplified form
- return L->isLoopSimplifyForm();
+ if (!L->isLoopSimplifyForm())
+ return false;
+ if (!DisableAdvancedPeeling)
+ return true;
+
+ SmallVector<BasicBlock *, 4> Exits;
+ L->getUniqueNonLatchExitBlocks(Exits);
+ // The latch must either be the only exiting block or all non-latch exit
+ // blocks have either a deopt or unreachable terminator or compose a chain of
+ // blocks where the last one is either deopt or unreachable terminated. Both
+ // deopt and unreachable terminators are a strong indication they are not
+ // taken. Note that this is a profitability check, not a legality check. Also
+ // note that LoopPeeling currently can only update the branch weights of latch
+ // blocks and branch weights to blocks with deopt or unreachable do not need
+ // updating.
+ return llvm::all_of(Exits, IsBlockFollowedByDeoptOrUnreachable);
}
// This function calculates the number of iterations after which the given Phi
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals
; RUN: opt < %s -S -loop-unroll -unroll-force-peel-count=2 2>&1 | FileCheck %s
+; RUN: opt < %s -S -loop-unroll -unroll-force-peel-count=2 -disable-advanced-peeling 2>&1 | FileCheck %s --check-prefix=DISABLEADV
declare i32 @get.x()
; CHECK-NEXT: br label [[LOOP_EXIT]]
; CHECK: loop.exit:
; CHECK-NEXT: ret void
-;
+
+; DISABLEADV-LABEL: @test()
+; DISABLEADV-NEXT: entry:
+; DISABLEADV-NEXT: br label %loop
+; DISABLEADV: loop
+; DISABLEADV-NEXT: %x = call i32 @get.x()
+; DISABLEADV-NEXT: switch i32 %x, label %loop.latch [
+; DISABLEADV-NEXT: i32 0, label %loop.latch
+; DISABLEADV-NEXT: i32 1, label %loop.exit
+; DISABLEADV-NEXT: i32 2, label %loop.exit
+; DISABLEADV-NEXT: ], !prof !0
+; DISABLEADV: loop.latch:
+; DISABLEADV-NEXT: br label %loop
+; DISABLEADV: loop.exit:
+; DISABLEADV-NEXT: ret void
+
entry:
br label %loop