[llvm] r317088 - Revert rL311205 "[IRCE] Fix buggy behavior in Clamp"
Max Kazantsev via llvm-commits
llvm-commits at lists.llvm.org
Wed Nov 1 06:21:56 PDT 2017
Author: mkazantsev
Date: Wed Nov 1 06:21:56 2017
New Revision: 317088
URL: http://llvm.org/viewvc/llvm-project?rev=317088&view=rev
Log:
Revert rL311205 "[IRCE] Fix buggy behavior in Clamp"
This patch reverts rL311205 that was initially a wrong fix. The real problem
was in intersection of signed and unsigned ranges (see rL316552), and the
patch being reverted masked the problem instead of fixing it.
By now, the test against which rL311205 was made works OK even without this
code. This revert patch also contains a test case that demonstrates incorrect
behavior caused by rL311205: it is caused by incorrect choise of signed max
instead of unsigned.
Modified:
llvm/trunk/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
llvm/trunk/test/Transforms/IRCE/clamp.ll
Modified: llvm/trunk/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp?rev=317088&r1=317087&r2=317088&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp Wed Nov 1 06:21:56 2017
@@ -1132,8 +1132,7 @@ LoopConstrainer::calculateSubRanges(bool
}
auto Clamp = [this, Smallest, Greatest, IsSignedPredicate](const SCEV *S) {
- bool MaybeNegativeValues = IsSignedPredicate || !SE.isKnownNonNegative(S);
- return MaybeNegativeValues
+ return IsSignedPredicate
? SE.getSMaxExpr(Smallest, SE.getSMinExpr(Greatest, S))
: SE.getUMaxExpr(Smallest, SE.getUMinExpr(Greatest, S));
};
Modified: llvm/trunk/test/Transforms/IRCE/clamp.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IRCE/clamp.ll?rev=317088&r1=317087&r2=317088&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/IRCE/clamp.ll (original)
+++ llvm/trunk/test/Transforms/IRCE/clamp.ll Wed Nov 1 06:21:56 2017
@@ -3,9 +3,13 @@
; The test demonstrates that incorrect behavior of Clamp may lead to incorrect
; calculation of post-loop exit condition.
-; CHECK: irce: in function test: constrained Loop at depth 1 containing: %loop<header><exiting>,%in_bounds<exiting>,%not_zero<latch><exiting>
+; CHECK-LABEL: irce: in function test_01: constrained Loop at depth 1 containing: %loop<header><exiting>,%in_bounds<exiting>,%not_zero<latch><exiting>
+; CHECK-LABEL: irce: in function test_02: constrained Loop at depth 1 containing: %loop<header><exiting>,%in_bounds<latch><exiting>
+
+define void @test_01() {
+
+; CHECK-LABEL: test_01
-define void @test() {
entry:
%indvars.iv.next467 = add nuw nsw i64 2, 1
%length.i167 = load i32, i32 addrspace(1)* undef, align 8
@@ -62,3 +66,62 @@ in_bounds:
%tmp107 = icmp ult i64 %indvars.iv.next, 2
br i1 %tmp107, label %not_zero, label %exit
}
+
+define void @test_02() {
+
+; CHECK-LABEL: test_02
+; CHECK-NOT: br i1 false, label %loop.preloop.preheader, label %preloop.pseudo.exit
+; CHECK-NOT: postloop
+; CHECK: entry:
+; CHECK-NEXT: br i1 true, label %loop.preloop.preheader, label %preloop.pseudo.exit
+; CHECK: mainloop:
+; CHECK-NEXT: br label %loop
+; CHECK: loop:
+; CHECK-NEXT: %iv1 = phi i64 [ %iv1.preloop.copy, %mainloop ], [ %iv1.next, %in_bounds ]
+; CHECK-NEXT: %iv2 = phi i64 [ %iv2.preloop.copy, %mainloop ], [ %iv2.next, %in_bounds ]
+; CHECK-NEXT: %iv2.offset = add i64 %iv2, 1
+; CHECK-NEXT: %rc = icmp ult i64 %iv2.offset, 400
+; CHECK-NEXT: br i1 true, label %in_bounds, label %bci_321.loopexit1
+; CHECK: in_bounds:
+; CHECK-NEXT: %iv1.next = add nuw nsw i64 %iv1, 2
+; CHECK-NEXT: %iv2.next = add nuw nsw i64 %iv2, 2
+; CHECK-NEXT: %cond = icmp ugt i64 %iv1, 204
+; CHECK-NEXT: br i1 %cond, label %bci_321.loopexit1, label %loop
+; CHECK: loop.preloop:
+; CHECK-NEXT: %iv1.preloop = phi i64 [ %iv1.next.preloop, %in_bounds.preloop ], [ 3, %loop.preloop.preheader ]
+; CHECK-NEXT: %iv2.preloop = phi i64 [ %iv2.next.preloop, %in_bounds.preloop ], [ 4294967295, %loop.preloop.preheader ]
+; CHECK-NEXT: %iv2.offset.preloop = add i64 %iv2.preloop, 1
+; CHECK-NEXT: %rc.preloop = icmp ult i64 %iv2.offset.preloop, 400
+; CHECK-NEXT: br i1 %rc.preloop, label %in_bounds.preloop, label %bci_321.loopexit
+; CHECK: in_bounds.preloop:
+; CHECK-NEXT: %iv1.next.preloop = add nuw nsw i64 %iv1.preloop, 2
+; CHECK-NEXT: %iv2.next.preloop = add nuw nsw i64 %iv2.preloop, 2
+; CHECK-NEXT: %cond.preloop = icmp ugt i64 %iv1.preloop, 204
+; CHECK-NEXT: [[C0:%[^ ]+]] = icmp ult i64 %iv1.preloop, 205
+; CHECK-NEXT: [[C1:%[^ ]+]] = xor i1 [[C0]], true
+; CHECK-NEXT: br i1 [[C1]], label %preloop.exit.selector, label %loop.preloop
+; CHECK: preloop.pseudo.exit:
+; CHECK-NEXT: %iv1.preloop.copy = phi i64 [ 3, %entry ], [ %iv1.next.preloop.lcssa, %preloop.exit.selector ]
+; CHECK-NEXT: %iv2.preloop.copy = phi i64 [ 4294967295, %entry ], [ %iv2.next.preloop.lcssa, %preloop.exit.selector ]
+; CHECK-NEXT: %indvar.end = phi i64 [ 1, %entry ], [ %iv1.preloop.lcssa, %preloop.exit.selector ]
+; CHECK-NEXT: br label %mainloop
+
+entry:
+ br label %loop
+
+loop: ; preds = %in_bounds, %entry
+ %iv1 = phi i64 [ 3, %entry ], [ %iv1.next, %in_bounds ]
+ %iv2 = phi i64 [ 4294967295, %entry ], [ %iv2.next, %in_bounds ]
+ %iv2.offset = add i64 %iv2, 1
+ %rc = icmp ult i64 %iv2.offset, 400
+ br i1 %rc, label %in_bounds, label %bci_321
+
+bci_321: ; preds = %in_bounds, %loop
+ ret void
+
+in_bounds: ; preds = %loop
+ %iv1.next = add nuw nsw i64 %iv1, 2
+ %iv2.next = add nuw nsw i64 %iv2, 2
+ %cond = icmp ugt i64 %iv1, 204
+ br i1 %cond, label %bci_321, label %loop
+}
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