3 files changed, 39 insertions, 0 deletions
diff --git a/source/slang/slang-ir-sccp.cpp b/source/slang/slang-ir-sccp.cpp
index fc3766e63..80cee8ecb 100644
--- a/source/slang/slang-ir-sccp.cpp
+++ b/source/slang/slang-ir-sccp.cpp
@@ -676,11 +676,23 @@ struct SCCPContext
     }
     LatticeVal evalLsh(IRType* type, LatticeVal v0, LatticeVal v1)
     {
+        IntInfo info = getIntTypeInfo(type);
+        if (info.isSigned == false)
+        {
+            return evalBinaryIntImpl(
+               type, v0, v1, [](IRUnsignedIntegerValue c0, IRUnsignedIntegerValue c1) { return c0 << c1; });
+        }
         return evalBinaryIntImpl(
             type, v0, v1, [](IRIntegerValue c0, IRIntegerValue c1) { return c0 << c1; });
     }
     LatticeVal evalRsh(IRType* type, LatticeVal v0, LatticeVal v1)
     {
+        IntInfo info = getIntTypeInfo(type);
+        if (info.isSigned == false)
+        {
+            return evalBinaryIntImpl(
+               type, v0, v1, [](IRUnsignedIntegerValue c0, IRUnsignedIntegerValue c1) { return c0 >> c1; });
+        }
         return evalBinaryIntImpl(
             type, v0, v1, [](IRIntegerValue c0, IRIntegerValue c1) { return c0 >> c1; });
     }
diff --git a/source/slang/slang-ir.h b/source/slang/slang-ir.h
index eb77127c8..36e145c01 100644
--- a/source/slang/slang-ir.h
+++ b/source/slang/slang-ir.h
@@ -1059,6 +1059,7 @@ void findAllInstsBreadthFirst(IRInst* inst, List<IRInst*>& outInsts);
 // Constant Instructions
 
 typedef int64_t IRIntegerValue;
+typedef uint64_t IRUnsignedIntegerValue;
 typedef double IRFloatingPointValue;
 
 struct IRConstant : IRInst
diff --git a/tests/bugs/gh-3637.slang b/tests/bugs/gh-3637.slang
new file mode 100644
index 000000000..81aa58c73
--- /dev/null
+++ b/tests/bugs/gh-3637.slang
@@ -0,0 +1,26 @@
+//TEST(compute):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-cuda -compute -output-using-type
+//TEST(compute, vulkan):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-vk -compute -output-using-type
+//TEST(compute):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-cpu -compute -output-using-type
+
+// CHECK: 9223372036854775808
+// CHECK: 1
+// CHECK: 18446744073709551615
+
+// This tests exhibits a bug in constant folding in which the right shift
+// operator unconditionally performs sign-extension.
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0 0 0 0 0], stride=8):out,name=outputBuffer
+RWStructuredBuffer<uint64_t> outputBuffer;
+
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID : SV_DispatchThreadID)
+{
+    const uint64_t topBitSet = 0x8000000000000000ull;
+    const uint64_t bottomBitSet = topBitSet >> 63;
+    const uint64_t allBitsSet = int64_t(topBitSet) >> 63; // expect sign-extending which will set all bits.
+    const uint64_t noBitsSet = topBitSet >> 64; // This exhibits undefined behaviour, as the compiler shifts right by at least the number of bits in the first operand
+    outputBuffer[0] = topBitSet;
+    outputBuffer[1] = bottomBitSet;
+    outputBuffer[2] = allBitsSet;
+    outputBuffer[3] = noBitsSet;
+}