[llvm] 2310e3e - [GlobalISel] Move DemandedElt's APInt size assert after isValid() check (#115979)

[via llvm-commits]

Author: Daniel Sanders
Date: 2024-11-18T15:39:28-08:00
New Revision: 2310e3e3f2ccdab156abc7f9d186b2605027d8fe

URL: https://github.com/llvm/llvm-project/commit/2310e3e3f2ccdab156abc7f9d186b2605027d8fe
DIFF: https://github.com/llvm/llvm-project/commit/2310e3e3f2ccdab156abc7f9d186b2605027d8fe.diff

LOG: [GlobalISel] Move DemandedElt's APInt size assert after isValid() check (#115979)

This prevents the assertion from wrongly triggering on invalid LLT's

Added: 
    

Modified: 
    llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp b/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
index 40d4a5250dfbbd..a700d866afa4ec 100644
--- a/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
@@ -147,6 +147,15 @@ void GISelKnownBits::computeKnownBitsImpl(Register R, KnownBits &Known,
   unsigned Opcode = MI.getOpcode();
   LLT DstTy = MRI.getType(R);
 
+  // Handle the case where this is called on a register that does not have a
+  // type constraint (i.e. it has a register class constraint instead). This is
+  // unlikely to occur except by looking through copies but it is possible for
+  // the initial register being queried to be in this state.
+  if (!DstTy.isValid()) {
+    Known = KnownBits();
+    return;
+  }
+
 #ifndef NDEBUG
   if (DstTy.isFixedVector()) {
     assert(
@@ -158,15 +167,6 @@ void GISelKnownBits::computeKnownBitsImpl(Register R, KnownBits &Known,
   }
 #endif
 
-  // Handle the case where this is called on a register that does not have a
-  // type constraint (i.e. it has a register class constraint instead). This is
-  // unlikely to occur except by looking through copies but it is possible for
-  // the initial register being queried to be in this state.
-  if (!DstTy.isValid()) {
-    Known = KnownBits();
-    return;
-  }
-
   unsigned BitWidth = DstTy.getScalarSizeInBits();
   auto CacheEntry = ComputeKnownBitsCache.find(R);
   if (CacheEntry != ComputeKnownBitsCache.end()) {