https://github.com/tbaederr created
https://github.com/llvm/llvm-project/pull/131633
None
>From 72ace33d6a7035f193728607095493d1a5d575ba Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbae...@redhat.com>
Date: Mon, 17 Mar 2025 17:01:38 +0100
Subject: [PATCH] [clang][bytecode] Fix builtin_memchr with non-0 start index
---
clang/lib/AST/ByteCode/InterpBuiltin.cpp | 8 +++++---
clang/test/AST/ByteCode/builtin-functions.cpp | 5 +++++
2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp
b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
index 4660c80fc90db..3fa8fbc22ec03 100644
--- a/clang/lib/AST/ByteCode/InterpBuiltin.cpp
+++ b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
@@ -2045,8 +2045,10 @@ static bool interp__builtin_memchr(InterpState &S,
CodePtr OpPC,
(ID == Builtin::BIstrchr || ID == Builtin::BI__builtin_strchr);
size_t Index = Ptr.getIndex();
+ size_t Step = 0;
for (;;) {
- const Pointer &ElemPtr = Index > 0 ? Ptr.atIndex(Index) : Ptr;
+ const Pointer &ElemPtr =
+ (Index + Step) > 0 ? Ptr.atIndex(Index + Step) : Ptr;
if (!CheckLoad(S, OpPC, ElemPtr))
return false;
@@ -2060,8 +2062,8 @@ static bool interp__builtin_memchr(InterpState &S,
CodePtr OpPC,
if (StopAtZero && V == 0)
break;
- ++Index;
- if (MaxLength && Index == MaxLength->getZExtValue())
+ ++Step;
+ if (MaxLength && Step == MaxLength->getZExtValue())
break;
}
diff --git a/clang/test/AST/ByteCode/builtin-functions.cpp
b/clang/test/AST/ByteCode/builtin-functions.cpp
index 29812553af9f0..11ff48bfa7102 100644
--- a/clang/test/AST/ByteCode/builtin-functions.cpp
+++ b/clang/test/AST/ByteCode/builtin-functions.cpp
@@ -1459,6 +1459,11 @@ namespace Memchr {
constexpr bool b = !memchr("hello", 'h', 3); // both-error {{constant
expression}} \
// both-note {{non-constexpr
function 'memchr' cannot be used in a constant expression}}
+ constexpr bool f() {
+ const char *c = "abcdef";
+ return __builtin_char_memchr(c + 1, 'f', 1) == nullptr;
+ }
+ static_assert(f());
}
namespace Strchr {
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