[llvm] [IR] Handle Scalable Vectors for 0 (PR #102205)

[Rose Silicon via llvm-commits]

https://github.com/RSilicon created https://github.com/llvm/llvm-project/pull/102205

None

>From 8ad8e9550b89d1d97fd4c9886386c15897ac06ca Mon Sep 17 00:00:00 2001
From: Rose <gfunni234 at gmail.com>
Date: Tue, 6 Aug 2024 15:42:15 -0400
Subject: [PATCH] [IR] Handle Scalable Vectors for 0

---
 llvm/include/llvm/IR/PatternMatch.h | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/llvm/include/llvm/IR/PatternMatch.h b/llvm/include/llvm/IR/PatternMatch.h
index 9c70a60bf50c7..e56153169d97c 100644
--- a/llvm/include/llvm/IR/PatternMatch.h
+++ b/llvm/include/llvm/IR/PatternMatch.h
@@ -603,8 +603,23 @@ inline cst_pred_ty<is_zero_int> m_ZeroInt() {
 struct is_zero {
   template <typename ITy> bool match(ITy *V) {
     auto *C = dyn_cast<Constant>(V);
-    // FIXME: this should be able to do something for scalable vectors
-    return C && (C->isNullValue() || cst_pred_ty<is_zero_int>().match(C));
+    if (C) {
+      if (C->isNullValue() || cst_pred_ty<is_zero_int>().match(C)) {
+        return true;
+      }
+    }
+
+    // Handle scalable vectors
+    if (auto *SV = dyn_cast<ScalableVectorType>(V->getType())) {
+      for (unsigned i = 0; i < SV->getNumElements(); ++i) {
+        if (!match(SV->getElementAsConstant(i))) {
+          return false;
+        }
+      }
+      return true;
+    }
+
+    return false;
   }
 };
 /// Match any null constant or a vector with all elements equal to 0.