From d77a3b61eba36bdd4c9585e5dfa3f779194d21c4 Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Wed, 13 Jul 2016 23:32:53 +0000
Subject: Move a transform from InstCombine to InstSimplify.

This transform doesn't require any new instructions, it can safely live
in InstSimplify.

llvm-svn: 275344
---
 llvm/lib/Analysis/InstructionSimplify.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'llvm/lib/Analysis/InstructionSimplify.cpp')

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 27c10ee..609cd26 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -3991,6 +3991,15 @@ static Value *SimplifyIntrinsic(Function *F, IterTy ArgBegin, IterTy ArgEnd,
                                   Q.DL);
   }
 
+  // Simplify calls to llvm.masked.load.*
+  if (IID == Intrinsic::masked_load) {
+    IterTy MaskArg = ArgBegin + 2;
+    // If the mask is all zeros, the "passthru" argument is the result.
+    if (auto *ConstMask = dyn_cast<Constant>(*MaskArg))
+      if (ConstMask->isNullValue())
+        return ArgBegin[3];
+  }
+
   // Perform idempotent optimizations
   if (!IsIdempotent(IID))
     return nullptr;
-- 
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