[llvm] fb2627d - [Test] Add test showing that SCEV cannot compute IV's range

[Max Kazantsev via llvm-commits]

Author: Max Kazantsev
Date: 2020-10-13T17:52:39+07:00
New Revision: fb2627d8d21574a0d1a81596d00953075265ac88

URL: https://github.com/llvm/llvm-project/commit/fb2627d8d21574a0d1a81596d00953075265ac88
DIFF: https://github.com/llvm/llvm-project/commit/fb2627d8d21574a0d1a81596d00953075265ac88.diff

LOG: [Test] Add test showing that SCEV cannot compute IV's range

Added: 
    llvm/test/Analysis/ScalarEvolution/no-wrap-symbolic-becount.ll

Modified: 
    

Removed: 
    


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diff  --git a/llvm/test/Analysis/ScalarEvolution/no-wrap-symbolic-becount.ll b/llvm/test/Analysis/ScalarEvolution/no-wrap-symbolic-becount.ll
new file mode 100644
index 000000000000..f9cb89c97161
--- /dev/null
+++ b/llvm/test/Analysis/ScalarEvolution/no-wrap-symbolic-becount.ll
@@ -0,0 +1,58 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py
+; RUN: opt < %s -S -analyze -scalar-evolution | FileCheck %s
+
+define i32 @test_01(i32 %start, i32* %p, i32* %q) {
+; CHECK-LABEL: 'test_01'
+; CHECK-NEXT:  Classifying expressions for: @test_01
+; CHECK-NEXT:    %0 = zext i32 %start to i64
+; CHECK-NEXT:    --> (zext i32 %start to i64) U: [0,4294967296) S: [0,4294967296)
+; CHECK-NEXT:    %indvars.iv = phi i64 [ %indvars.iv.next, %backedge ], [ %0, %entry ]
+; CHECK-NEXT:    --> {(zext i32 %start to i64),+,-1}<nsw><%loop> U: [-4294967295,4294967296) S: [-4294967295,4294967296) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %iv = phi i32 [ %start, %entry ], [ %iv.next, %backedge ]
+; CHECK-NEXT:    --> {%start,+,-1}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %iv.next = add i32 %iv, -1
+; CHECK-NEXT:    --> {(-1 + %start),+,-1}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %index = zext i32 %iv.next to i64
+; CHECK-NEXT:    --> (zext i32 {(-1 + %start),+,-1}<%loop> to i64) U: [0,4294967296) S: [0,4294967296) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %store.addr = getelementptr i32, i32* %p, i64 %index
+; CHECK-NEXT:    --> ((4 * (zext i32 {(-1 + %start),+,-1}<%loop> to i64))<nuw><nsw> + %p) U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %load.addr = getelementptr i32, i32* %q, i64 %index
+; CHECK-NEXT:    --> ((4 * (zext i32 {(-1 + %start),+,-1}<%loop> to i64))<nuw><nsw> + %q) U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:    %stop = load i32, i32* %load.addr, align 4
+; CHECK-NEXT:    --> %stop U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Variant }
+; CHECK-NEXT:    %indvars.iv.next = add nsw i64 %indvars.iv, -1
+; CHECK-NEXT:    --> {(-1 + (zext i32 %start to i64))<nsw>,+,-1}<nsw><%loop> U: [-4294967296,4294967295) S: [-4294967296,4294967295) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT:  Determining loop execution counts for: @test_01
+; CHECK-NEXT:  Loop %loop: <multiple exits> Unpredictable backedge-taken count.
+; CHECK-NEXT:    exit count for loop: (zext i32 %start to i64)
+; CHECK-NEXT:    exit count for backedge: ***COULDNOTCOMPUTE***
+; CHECK-NEXT:  Loop %loop: max backedge-taken count is 4294967295
+; CHECK-NEXT:  Loop %loop: Unpredictable predicated backedge-taken count.
+;
+entry:
+  %0 = zext i32 %start to i64
+  br label %loop
+
+loop:                                             ; preds = %backedge, %entry
+  %indvars.iv = phi i64 [ %indvars.iv.next, %backedge ], [ %0, %entry ]
+  %iv = phi i32 [ %start, %entry ], [ %iv.next, %backedge ]
+  %cond = icmp eq i64 %indvars.iv, 0
+  br i1 %cond, label %exit, label %backedge
+
+backedge:                                         ; preds = %loop
+  %iv.next = add i32 %iv, -1
+  %index = zext i32 %iv.next to i64
+  %store.addr = getelementptr i32, i32* %p, i64 %index
+  store i32 1, i32* %store.addr, align 4
+  %load.addr = getelementptr i32, i32* %q, i64 %index
+  %stop = load i32, i32* %load.addr, align 4
+  %loop.cond = icmp eq i32 %stop, 0
+  %indvars.iv.next = add nsw i64 %indvars.iv, -1
+  br i1 %loop.cond, label %loop, label %failure
+
+exit:                                             ; preds = %loop
+  ret i32 0
+
+failure:                                          ; preds = %backedge
+  unreachable
+}