From 3f2ff7cc8ca9a5ba28ac2b25e957a706c8f6491c Mon Sep 17 00:00:00 2001 From: Max Kazantsev Date: Mon, 21 Jun 2021 13:11:15 +0700 Subject: [PATCH] [Test] Add some tests showing room for optimization exploiting undef and UB --- .../LoopDeletion/eval_first_iteration.ll | 222 ++++++++++++++++++ 1 file changed, 222 insertions(+) diff --git a/llvm/test/Transforms/LoopDeletion/eval_first_iteration.ll b/llvm/test/Transforms/LoopDeletion/eval_first_iteration.ll index 744853e23a2a..15ebd7db7624 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(