[llvm] 3f2ff7c - [Test] Add some tests showing room for optimization exploiting undef and UB
Max Kazantsev via llvm-commits
llvm-commits at lists.llvm.org
Sun Jun 20 23:12:06 PDT 2021
Author: Max Kazantsev
Date: 2021-06-21T13:11:46+07:00
New Revision: 3f2ff7cc8ca9a5ba28ac2b25e957a706c8f6491c
URL: https://github.com/llvm/llvm-project/commit/3f2ff7cc8ca9a5ba28ac2b25e957a706c8f6491c
DIFF: https://github.com/llvm/llvm-project/commit/3f2ff7cc8ca9a5ba28ac2b25e957a706c8f6491c.diff
LOG: [Test] Add some tests showing room for optimization exploiting undef and UB
Added:
Modified:
llvm/test/Transforms/LoopDeletion/eval_first_iteration.ll
Removed:
################################################################################
diff --git a/llvm/test/Transforms/LoopDeletion/eval_first_iteration.ll b/llvm/test/Transforms/LoopDeletion/eval_first_iteration.ll
index 744853e23a2a3..15ebd7db7624f 100644
--- a/llvm/test/Transforms/LoopDeletion/eval_first_iteration.ll
+++ b/llvm/test/Transforms/LoopDeletion/eval_first_iteration.ll
@@ -731,6 +731,228 @@ failure:
unreachable
}
+; TODO: We can break the backedge here by assuming that undef = sub.
+define i32 @test_multiple_pred_undef_1() {
+; CHECK-LABEL: @test_multiple_pred_undef_1(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[SUM:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[SUM_NEXT:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT: [[SUB:%.*]] = sub i32 4, [[SUM]]
+; CHECK-NEXT: [[IS_POSITIVE:%.*]] = icmp sgt i32 [[SUB]], 0
+; CHECK-NEXT: br i1 [[IS_POSITIVE]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
+; CHECK: if.true:
+; CHECK-NEXT: br i1 undef, label [[IF_TRUE_1:%.*]], label [[IF_TRUE_2:%.*]]
+; CHECK: if.true.1:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: if.true.2:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: if.false:
+; CHECK-NEXT: br i1 undef, label [[IF_FALSE_1:%.*]], label [[IF_FALSE_2:%.*]]
+; CHECK: if.false.1:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: if.false.2:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: backedge:
+; CHECK-NEXT: [[MERGE_PHI:%.*]] = phi i32 [ 0, [[IF_FALSE_1]] ], [ 0, [[IF_FALSE_2]] ], [ [[SUB]], [[IF_TRUE_1]] ], [ undef, [[IF_TRUE_2]] ]
+; CHECK-NEXT: [[SUM_NEXT]] = add i32 [[SUM]], [[MERGE_PHI]]
+; CHECK-NEXT: [[LOOP_COND:%.*]] = icmp ne i32 [[SUM_NEXT]], 4
+; CHECK-NEXT: br i1 [[LOOP_COND]], label [[LOOP]], label [[DONE:%.*]]
+; CHECK: done:
+; CHECK-NEXT: [[SUM_NEXT_LCSSA:%.*]] = phi i32 [ [[SUM_NEXT]], [[BACKEDGE]] ]
+; CHECK-NEXT: ret i32 [[SUM_NEXT_LCSSA]]
+; CHECK: failure:
+; CHECK-NEXT: unreachable
+;
+entry:
+ br label %loop
+
+loop: ; preds = %backedge, %entry
+ %sum = phi i32 [ 0, %entry ], [ %sum.next, %backedge ]
+ %sub = sub i32 4, %sum
+ %is.positive = icmp sgt i32 %sub, 0
+ br i1 %is.positive, label %if.true, label %if.false
+
+if.true:
+ br i1 undef, label %if.true.1, label %if.true.2
+
+if.true.1:
+ br label %backedge
+
+if.true.2:
+ br label %backedge
+
+if.false: ; preds = %loop
+ br i1 undef, label %if.false.1, label %if.false.2
+
+if.false.1:
+ br label %backedge
+
+if.false.2:
+ br label %backedge
+
+backedge:
+ %merge.phi = phi i32 [ 0, %if.false.1 ], [ 0, %if.false.2 ], [ %sub, %if.true.1 ], [ undef, %if.true.2 ]
+ %sum.next = add i32 %sum, %merge.phi
+ %loop.cond = icmp ne i32 %sum.next, 4
+ br i1 %loop.cond, label %loop, label %done
+
+done: ; preds = %backedge
+ %sum.next.lcssa = phi i32 [ %sum.next, %backedge ]
+ ret i32 %sum.next.lcssa
+
+failure:
+ unreachable
+}
+
+; TODO: We can break the backedge here by assuming that undef = sub.
+define i32 @test_multiple_pred_undef_2() {
+; CHECK-LABEL: @test_multiple_pred_undef_2(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[SUM:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[SUM_NEXT:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT: [[SUB:%.*]] = sub i32 4, [[SUM]]
+; CHECK-NEXT: [[IS_POSITIVE:%.*]] = icmp sgt i32 [[SUB]], 0
+; CHECK-NEXT: br i1 [[IS_POSITIVE]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
+; CHECK: if.true:
+; CHECK-NEXT: br i1 undef, label [[IF_TRUE_1:%.*]], label [[IF_TRUE_2:%.*]]
+; CHECK: if.true.1:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: if.true.2:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: if.false:
+; CHECK-NEXT: br i1 undef, label [[IF_FALSE_1:%.*]], label [[IF_FALSE_2:%.*]]
+; CHECK: if.false.1:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: if.false.2:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: backedge:
+; CHECK-NEXT: [[MERGE_PHI:%.*]] = phi i32 [ 0, [[IF_FALSE_1]] ], [ 0, [[IF_FALSE_2]] ], [ undef, [[IF_TRUE_1]] ], [ [[SUB]], [[IF_TRUE_2]] ]
+; CHECK-NEXT: [[SUM_NEXT]] = add i32 [[SUM]], [[MERGE_PHI]]
+; CHECK-NEXT: [[LOOP_COND:%.*]] = icmp ne i32 [[SUM_NEXT]], 4
+; CHECK-NEXT: br i1 [[LOOP_COND]], label [[LOOP]], label [[DONE:%.*]]
+; CHECK: done:
+; CHECK-NEXT: [[SUM_NEXT_LCSSA:%.*]] = phi i32 [ [[SUM_NEXT]], [[BACKEDGE]] ]
+; CHECK-NEXT: ret i32 [[SUM_NEXT_LCSSA]]
+; CHECK: failure:
+; CHECK-NEXT: unreachable
+;
+entry:
+ br label %loop
+
+loop: ; preds = %backedge, %entry
+ %sum = phi i32 [ 0, %entry ], [ %sum.next, %backedge ]
+ %sub = sub i32 4, %sum
+ %is.positive = icmp sgt i32 %sub, 0
+ br i1 %is.positive, label %if.true, label %if.false
+
+if.true:
+ br i1 undef, label %if.true.1, label %if.true.2
+
+if.true.1:
+ br label %backedge
+
+if.true.2:
+ br label %backedge
+
+if.false: ; preds = %loop
+ br i1 undef, label %if.false.1, label %if.false.2
+
+if.false.1:
+ br label %backedge
+
+if.false.2:
+ br label %backedge
+
+backedge:
+ %merge.phi = phi i32 [ 0, %if.false.1 ], [ 0, %if.false.2 ], [ undef, %if.true.1 ], [ %sub, %if.true.2 ]
+ %sum.next = add i32 %sum, %merge.phi
+ %loop.cond = icmp ne i32 %sum.next, 4
+ br i1 %loop.cond, label %loop, label %done
+
+done: ; preds = %backedge
+ %sum.next.lcssa = phi i32 [ %sum.next, %backedge ]
+ ret i32 %sum.next.lcssa
+
+failure:
+ unreachable
+}
+
+; TODO: We can break the backedge here by exploiting undef.
+define i32 @test_multiple_pred_undef_3() {
+; CHECK-LABEL: @test_multiple_pred_undef_3(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[SUM:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[SUM_NEXT:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT: [[SUB:%.*]] = sub i32 4, [[SUM]]
+; CHECK-NEXT: [[IS_POSITIVE:%.*]] = icmp sgt i32 [[SUB]], 0
+; CHECK-NEXT: br i1 [[IS_POSITIVE]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
+; CHECK: if.true:
+; CHECK-NEXT: br i1 undef, label [[IF_TRUE_1:%.*]], label [[IF_TRUE_2:%.*]]
+; CHECK: if.true.1:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: if.true.2:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: if.false:
+; CHECK-NEXT: br i1 undef, label [[IF_FALSE_1:%.*]], label [[IF_FALSE_2:%.*]]
+; CHECK: if.false.1:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: if.false.2:
+; CHECK-NEXT: br label [[BACKEDGE]]
+; CHECK: backedge:
+; CHECK-NEXT: [[MERGE_PHI:%.*]] = phi i32 [ 0, [[IF_FALSE_1]] ], [ 0, [[IF_FALSE_2]] ], [ undef, [[IF_TRUE_1]] ], [ undef, [[IF_TRUE_2]] ]
+; CHECK-NEXT: [[SUM_NEXT]] = add i32 [[SUM]], [[MERGE_PHI]]
+; CHECK-NEXT: [[LOOP_COND:%.*]] = icmp ne i32 [[SUM_NEXT]], 4
+; CHECK-NEXT: br i1 [[LOOP_COND]], label [[LOOP]], label [[DONE:%.*]]
+; CHECK: done:
+; CHECK-NEXT: [[SUM_NEXT_LCSSA:%.*]] = phi i32 [ [[SUM_NEXT]], [[BACKEDGE]] ]
+; CHECK-NEXT: ret i32 [[SUM_NEXT_LCSSA]]
+; CHECK: failure:
+; CHECK-NEXT: unreachable
+;
+entry:
+ br label %loop
+
+loop: ; preds = %backedge, %entry
+ %sum = phi i32 [ 0, %entry ], [ %sum.next, %backedge ]
+ %sub = sub i32 4, %sum
+ %is.positive = icmp sgt i32 %sub, 0
+ br i1 %is.positive, label %if.true, label %if.false
+
+if.true:
+ br i1 undef, label %if.true.1, label %if.true.2
+
+if.true.1:
+ br label %backedge
+
+if.true.2:
+ br label %backedge
+
+if.false: ; preds = %loop
+ br i1 undef, label %if.false.1, label %if.false.2
+
+if.false.1:
+ br label %backedge
+
+if.false.2:
+ br label %backedge
+
+backedge:
+ %merge.phi = phi i32 [ 0, %if.false.1 ], [ 0, %if.false.2 ], [ undef, %if.true.1 ], [ undef, %if.true.2 ]
+ %sum.next = add i32 %sum, %merge.phi
+ %loop.cond = icmp ne i32 %sum.next, 4
+ br i1 %loop.cond, label %loop, label %done
+
+done: ; preds = %backedge
+ %sum.next.lcssa = phi i32 [ %sum.next, %backedge ]
+ ret i32 %sum.next.lcssa
+
+failure:
+ unreachable
+}
+
; TODO: We can break the backedge here.
define i32 @test_select(i32 %limit) {
; CHECK-LABEL: @test_select(
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