[llvm] f7de5bb - [Test] Add test for PR60234
Max Kazantsev via llvm-commits
llvm-commits at lists.llvm.org
Mon Jan 23 04:38:29 PST 2023
Author: Max Kazantsev
Date: 2023-01-23T19:38:10+07:00
New Revision: f7de5bb9e893193bf3d7a8e2d952d85a5c9939e8
URL: https://github.com/llvm/llvm-project/commit/f7de5bb9e893193bf3d7a8e2d952d85a5c9939e8
DIFF: https://github.com/llvm/llvm-project/commit/f7de5bb9e893193bf3d7a8e2d952d85a5c9939e8.diff
LOG: [Test] Add test for PR60234
https://github.com/llvm/llvm-project/issues/60234 explains how widening
of a branch by loop-invariant condition is causing a miscompile.
Added:
llvm/test/Transforms/GuardWidening/pr60234.ll
Modified:
Removed:
################################################################################
diff --git a/llvm/test/Transforms/GuardWidening/pr60234.ll b/llvm/test/Transforms/GuardWidening/pr60234.ll
new file mode 100644
index 000000000000..f428d04e0ca2
--- /dev/null
+++ b/llvm/test/Transforms/GuardWidening/pr60234.ll
@@ -0,0 +1,76 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -passes=indvars,guard-widening -S < %s | FileCheck %s
+
+declare i32 @llvm.experimental.deoptimize.i32(...)
+
+; FIXME: Make sure that guard widening does not turn loop-invariant condition
+; (that then gets optimized basing on this fact) into non-invariant.
+; https://github.com/llvm/llvm-project/issues/60234 explains how it causes
+; a miscompile.
+define i32 @test(i32 %start) {
+; CHECK-LABEL: @test(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[WC1:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT: br label [[LOOP:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[IV:%.*]] = phi i32 [ [[START:%.*]], [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT: [[START_PLUS_1:%.*]] = add i32 [[START]], 1
+; CHECK-NEXT: [[COND:%.*]] = icmp ne i32 [[START_PLUS_1]], [[IV]]
+; CHECK-NEXT: [[WIDE_CHK:%.*]] = and i1 true, [[COND]]
+; CHECK-NEXT: [[TMP0:%.*]] = and i1 [[WIDE_CHK]], [[WC1]]
+; CHECK-NEXT: br i1 [[TMP0]], label [[GUARD_BLOCK:%.*]], label [[EXIT_BY_WC:%.*]]
+; CHECK: exit_by_wc:
+; CHECK-NEXT: [[IV_LCSSA:%.*]] = phi i32 [ [[START]], [[LOOP]] ]
+; CHECK-NEXT: [[RVAL1:%.*]] = call i32 (...) @llvm.experimental.deoptimize.i32() [ "deopt"(i32 [[IV_LCSSA]]) ]
+; CHECK-NEXT: ret i32 [[RVAL1]]
+; CHECK: guard_block:
+; CHECK-NEXT: [[WC2:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT: [[GUARD:%.*]] = and i1 [[COND]], [[WC2]]
+; CHECK-NEXT: br i1 true, label [[BACKEDGE]], label [[FAILURE:%.*]]
+; CHECK: backedge:
+; CHECK-NEXT: call void @side_effect()
+; CHECK-NEXT: [[IV_NEXT]] = add i32 [[IV]], 1
+; CHECK-NEXT: br label [[LOOP]]
+; CHECK: exit:
+; CHECK-NEXT: ret i32 -1
+; CHECK: failure:
+; CHECK-NEXT: [[IV_LCSSA1:%.*]] = phi i32 [ [[IV]], [[GUARD_BLOCK]] ]
+; CHECK-NEXT: [[RVAL2:%.*]] = call i32 (...) @llvm.experimental.deoptimize.i32() [ "deopt"(i32 [[IV_LCSSA1]]) ]
+; CHECK-NEXT: ret i32 [[RVAL2]]
+;
+entry:
+ %wc1 = call i1 @llvm.experimental.widenable.condition()
+ br label %loop
+
+loop:
+ %iv = phi i32 [ %start, %entry ], [ %iv.next, %backedge ]
+ br i1 %wc1, label %guard_block, label %exit_by_wc
+
+exit_by_wc:
+ %rval1 = call i32(...) @llvm.experimental.deoptimize.i32() [ "deopt"(i32 %iv) ]
+ ret i32 %rval1
+
+guard_block:
+ %start_plus_1 = add i32 %start, 1
+ %cond = icmp ne i32 %start_plus_1, %iv
+ %wc2 = call i1 @llvm.experimental.widenable.condition()
+ %guard = and i1 %cond, %wc2
+ br i1 %guard, label %backedge, label %failure
+
+backedge:
+ call void @side_effect()
+ %iv.next = add i32 %iv, 1
+ br label %loop
+
+exit:
+ ret i32 -1
+
+failure:
+ %rval2 = call i32(...) @llvm.experimental.deoptimize.i32() [ "deopt"(i32 %iv) ]
+ ret i32 %rval2
+}
+
+; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(inaccessiblemem: readwrite)
+declare i1 @llvm.experimental.widenable.condition()
+
+declare void @side_effect()
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