================
@@ -0,0 +1,90 @@
+; NOTE: Assertions have been autogenerated by
utils/update_analyze_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -disable-output "-passes=print<da>" 2>&1 | FileCheck %s
+
+; Test case for GitHub issue #149501: DA bound check with symbolic expressions.
+; The issue occurs when symbolic upper bounds and deltas create impossible
runtime assumptions.
+; Our fix improves the bound check logic to handle these cases more gracefully.
+
+; Case 1: Symbolic case that was problematic - improved bound checking.
+define void @f_symbolic(ptr %a, i64 %n, i64 %m) {
+; CHECK-LABEL: 'f_symbolic'
+; CHECK-NEXT: Src: store i8 40, ptr %idx.0, align 1 --> Dst: store i8 40, ptr
%idx.0, align 1
+; CHECK-NEXT: da analyze - none!
+; CHECK-NEXT: Src: store i8 40, ptr %idx.0, align 1 --> Dst: store i8 42, ptr
%idx.1, align 1
+; CHECK-NEXT: da analyze - consistent output [*|<]!
+; CHECK-NEXT: Src: store i8 42, ptr %idx.1, align 1 --> Dst: store i8 42, ptr
%idx.1, align 1
+; CHECK-NEXT: da analyze - none!
+;
+entry:
+ %bound = sub i64 %m, %n
+ br label %loop
+
+loop:
+ %i = phi i64 [ 0, %entry ], [ %i.next, %loop ]
+ %subscript.0 = add i64 %i, %n
+ %subscript.1 = add i64 %i, %m
+ %idx.0 = getelementptr i8, ptr %a, i64 %subscript.0
+ %idx.1 = getelementptr i8, ptr %a, i64 %subscript.1
+ store i8 40, ptr %idx.0
+ store i8 42, ptr %idx.1
+ %i.next = add i64 %i, 1
+ %cond.exit = icmp eq i64 %i.next, %bound
+ br i1 %cond.exit, label %exit, label %loop
+
+exit:
+ ret void
+}
+
+; Case 2: Case with negative bound - correctly handled by improved bound check.
+define void @f_negative_bound(ptr %a) {
+; CHECK-LABEL: 'f_negative_bound'
+; CHECK-NEXT: Src: store i8 40, ptr %idx.0, align 1 --> Dst: store i8 40, ptr
%idx.0, align 1
+; CHECK-NEXT: da analyze - none!
+; CHECK-NEXT: Src: store i8 40, ptr %idx.0, align 1 --> Dst: store i8 42, ptr
%idx.1, align 1
+; CHECK-NEXT: da analyze - none!
+; CHECK-NEXT: Src: store i8 42, ptr %idx.1, align 1 --> Dst: store i8 42, ptr
%idx.1, align 1
+; CHECK-NEXT: da analyze - none!
+;
+entry:
+ br label %loop
+
+loop:
+ %i = phi i64 [ 0, %entry ], [ %i.next, %loop ]
+ %idx.0 = getelementptr i8, ptr %a, i64 %i
+ %idx.1 = getelementptr i8, ptr %a, i64 %i
+ store i8 40, ptr %idx.0
+ store i8 42, ptr %idx.1
+ %i.next = add i64 %i, 1
+ %cond.exit = icmp eq i64 %i.next, 0 ; bound = 0 (negative upper bound)
----------------
sjoerdmeijer wrote:
I think I agree with @kasuga-fj , this doesn't look right. If I haven't made a
mistake `i` starts with value 1, it is compared against 0 which is false, and
branch back to label %loop:
%i.next = 1
%i.next != 0
br %loop
so, this loop executes 2^64 times.
Also, when I run this example with `bin/opt -disable-output
"-passes=print<da>"` I see the same output, so doesn't look like this patch
changes anything for this example.
Maybe we should pre-commit test cases so we can see better what changes, if we
think this is a good test case to add.
https://github.com/llvm/llvm-project/pull/157761
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