[llvm] 0737770 - [LVI][CVP] Add test for miscompilation by CVP due to incorrect range returned by LVI

[Dmitry Makogon via llvm-commits]

Author: Dmitry Makogon
Date: 2023-02-10T17:06:35+07:00
New Revision: 0737770c3e1d5e119148351610c39fb2483c7011

URL: https://github.com/llvm/llvm-project/commit/0737770c3e1d5e119148351610c39fb2483c7011
DIFF: https://github.com/llvm/llvm-project/commit/0737770c3e1d5e119148351610c39fb2483c7011.diff

LOG: [LVI][CVP] Add test for miscompilation by CVP due to incorrect range returned by LVI

This adds a test case from PR60629 which shows a miscompilation by CVP.

Added: 
    llvm/test/Analysis/LazyValueAnalysis/pr60629.ll

Modified: 
    

Removed: 
    


################################################################################
diff  --git a/llvm/test/Analysis/LazyValueAnalysis/pr60629.ll b/llvm/test/Analysis/LazyValueAnalysis/pr60629.ll
new file mode 100644
index 0000000000000..feae45bc6e214
--- /dev/null
+++ b/llvm/test/Analysis/LazyValueAnalysis/pr60629.ll
@@ -0,0 +1,48 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -passes=correlated-propagation -S %s | FileCheck %s
+
+; XFAIL: *
+
+; Check that shift is not removed by CVP because of incorrect range returned by LVI::getConstantRangeAtUse.
+; https://github.com/llvm/llvm-project/issues/60629
+
+define i32 @test(i32 %arg) {
+; CHECK-LABEL: @test(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 127, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[DO_SHIFT:%.*]] ]
+; CHECK-NEXT:    [[SHIFTED_IV:%.*]] = phi i32 [ 0, [[ENTRY]] ], [ [[SHIFT:%.*]], [[DO_SHIFT]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = add i32 [[IV]], 1
+; CHECK-NEXT:    [[LOOP_COND:%.*]] = icmp sgt i32 [[IV]], 127
+; CHECK-NEXT:    br i1 [[LOOP_COND]], label [[EXIT:%.*]], label [[DO_SHIFT]]
+; CHECK:       do.shift:
+; CHECK-NEXT:    [[SHIFT]] = ashr i32 [[IV]], [[ARG:%.*]]
+; CHECK-NEXT:    br label [[LOOP]]
+; CHECK:       bb1:
+; CHECK-NEXT:    br label [[EXIT]]
+; CHECK:       exit:
+; CHECK-NEXT:    [[RETVAL:%.*]] = phi i32 [ 0, [[BB1:%.*]] ], [ [[SHIFTED_IV]], [[LOOP]] ]
+; CHECK-NEXT:    ret i32 [[RETVAL]]
+;
+entry:
+  br label %loop
+
+loop:                                              ; preds = %do.shift, %entry
+  %iv = phi i32 [ 127, %entry ], [ %iv.next, %do.shift ]
+  %shifted.iv = phi i32 [ 0, %entry ], [ %shift, %do.shift ]
+  %iv.next = add i32 %iv, 1
+  %loop_cond = icmp sgt i32 %iv, 127
+  br i1 %loop_cond, label %exit, label %do.shift
+
+do.shift:                                          ; preds = %loop
+  %shift = ashr i32 %iv, %arg
+  br label %loop
+
+bb1:                                               ; No predecessors!
+  br label %exit
+
+exit:                                              ; preds = %loop, %bb1
+  %retval = phi i32 [ 0, %bb1 ], [ %shifted.iv, %loop ]
+  ret i32 %retval
+}