[clang] [CLANG] Resolves crash on invalid loop vectorize_width (PR #169473)

[Ebin Jose via cfe-commits]

https://github.com/ebinjose02 created https://github.com/llvm/llvm-project/pull/169473

Fixes #166325
Diagnose malformed '#pragma clang loop vectorize_width' lists. Avoids crash in HandlePragmaLoopHint, emit clear diagnostic and added regression test.

>From 73761f8d62f505901eef4b845cccca98b1bc21ee Mon Sep 17 00:00:00 2001
From: ebinjose02 <ebin371 at gmail.com>
Date: Tue, 25 Nov 2025 08:54:39 +0000
Subject: [PATCH] Fixes #166325 Diagnose malformed '#pragma clang loop
 vectorize_width' lists. Avoids crash in HandlePragmaLoopHint, emit clear
 diagnostic and added regression test.

---
 clang/lib/Parse/ParsePragma.cpp             |  2 +-
 clang/test/Parser/pragma-loop-vectorize.cpp | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)
 create mode 100644 clang/test/Parser/pragma-loop-vectorize.cpp

diff --git a/clang/lib/Parse/ParsePragma.cpp b/clang/lib/Parse/ParsePragma.cpp
index 7c2b9280f0b76..7e8b339f5be49 100644
--- a/clang/lib/Parse/ParsePragma.cpp
+++ b/clang/lib/Parse/ParsePragma.cpp
@@ -1531,7 +1531,7 @@ bool Parser::HandlePragmaLoopHint(LoopHint &Hint) {
         PP.Lex(Tok); // ,
 
         StateInfo = Tok.getIdentifierInfo();
-        IsScalableStr = StateInfo->getName();
+        IsScalableStr = StateInfo ? StateInfo->getName() : "";
 
         if (IsScalableStr != "scalable" && IsScalableStr != "fixed") {
           Diag(Tok.getLocation(),
diff --git a/clang/test/Parser/pragma-loop-vectorize.cpp b/clang/test/Parser/pragma-loop-vectorize.cpp
new file mode 100644
index 0000000000000..39f7e84323f5f
--- /dev/null
+++ b/clang/test/Parser/pragma-loop-vectorize.cpp
@@ -0,0 +1,13 @@
+// RUN: not %clang_cc1 -fsyntax-only %s 2>&1 | FileCheck %s
+
+void sum_vector(unsigned int A[], unsigned int B[], unsigned int sum[]) {
+    #pragma clang loop vectorize_width(4,8,16) vectorize(assume_safety)
+    for (int k = 0; k < 64; k++) {
+        sum[k] = A[k] + 3 * B[k];
+    }
+}
+
+// CHECK: error: vectorize_width loop hint malformed; use
+// CHECK-SAME: vectorize_width(X, fixed) or vectorize_width(X, scalable) where X is an integer, or
+// CHECK-SAME: vectorize_width('fixed' or 'scalable')
+// CHECK: warning: extra tokens at end of '#pragma clang loop vectorize_width'