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[IRCE] Be resilient in the face of non-simplified loops

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Loops containing `indirectbr` may not be in simplified form, even after
running LoopSimplify.  Reject then gracefully, instead of tripping an
assert.

llvm-svn: 278611
This commit is contained in:
Sanjoy Das 2016-08-13 23:36:35 +00:00
parent a76cb44305
commit 6c4db87c1a
2 changed files with 42 additions and 2 deletions
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5
lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
View File

@ -622,9 +622,12 @@ static bool CanBeSMin(ScalarEvolution &SE, const SCEV *S) {
Optional<LoopStructure>
LoopStructure::parseLoopStructure(ScalarEvolution &SE, BranchProbabilityInfo &BPI,
Loop &L, const char *&FailureReason) {
assert(L.isLoopSimplifyForm() && "should follow from addRequired<>");
if (!L.isLoopSimplifyForm())
return None;
BasicBlock *Latch = L.getLoopLatch();
assert(Latch && "Simplified loops only have one latch!");
if (!L.isLoopExiting(Latch)) {
FailureReason = "no loop latch";
return None;

39
test/Transforms/IRCE/unhandled.ll
View File

@ -1,11 +1,12 @@
; RUN: opt -irce-print-changed-loops -irce -S < %s 2>&1 | FileCheck %s
; CHECK-NOT: constrained Loop at depth
; Demonstrates that we don't currently handle the general expression
; `A * I + B'.
define void @general_affine_expressions(i32 *%arr, i32 *%a_len_ptr, i32 %n,
i32 %scale, i32 %offset) {
; CHECK-NOT: constrained Loop at depth
entry:
%len = load i32, i32* %a_len_ptr, !range !0
%first.itr.check = icmp sgt i32 %n, 0
@ -34,4 +35,40 @@ define void @general_affine_expressions(i32 *%arr, i32 *%a_len_ptr, i32 %n,
ret void
}
; Check that we do the right thing for a loop that could not be
; simplified due to an indirectbr.
define void @multiple_latches(i32 *%arr, i32 *%a_len_ptr, i32 %n) {
entry:
%len = load i32, i32* %a_len_ptr, !range !0
%n.add.1 = add i32 %n, 1
%first.itr.check = icmp sgt i32 %n, 0
br i1 %first.itr.check, label %loop, label %exit
loop:
%idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ], [ %idx.next, %continue ]
%idx.next = add i32 %idx, 1
%idx.next2 = add i32 %idx, 2
%abc = icmp slt i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds, !prof !1
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp slt i32 %idx.next, %n
br i1 %next, label %loop, label %continue
continue:
%next2 = icmp slt i32 %idx.next, %n.add.1
%dest = select i1 %next2, i8* blockaddress(@multiple_latches, %loop), i8* blockaddress(@multiple_latches, %exit)
indirectbr i8* %dest, [ label %loop, label %exit]
out.of.bounds:
ret void
exit:
ret void
}
!0 = !{i32 0, i32 2147483647}
!1 = !{!"branch_weights", i32 64, i32 4}