diff --git a/lib/Dialect/TritonGPU/Transforms/Pipeline.cpp b/lib/Dialect/TritonGPU/Transforms/Pipeline.cpp
index a4db60380..32dc88e25 100644
--- a/lib/Dialect/TritonGPU/Transforms/Pipeline.cpp
+++ b/lib/Dialect/TritonGPU/Transforms/Pipeline.cpp
@@ -269,7 +269,9 @@ scf::ForOp LoopPipeliner::createNewForOp() {
       Value newMask = builder.create<arith::AndIOp>(mask.getLoc(),
                                                     splatCond,
                                                     nextMapping.lookupOrDefault(mask));
-      nextMapping.map(mask, newMask);
+      // if mask is defined outside the loop, don't update the map more than once
+      if (!(forOp.isDefinedOutsideOfLoop(mask) && nextMapping.contains(mask)))
+        nextMapping.map(mask, newMask);
     }
     Operation *nextOp = builder.clone(*op, nextMapping);
     // update mapping of results
diff --git a/rewrite-test/jit/matmul/matmul.mlir b/rewrite-test/jit/matmul/matmul.mlir
index fd2268ead..a70dfd334 100644
--- a/rewrite-test/jit/matmul/matmul.mlir
+++ b/rewrite-test/jit/matmul/matmul.mlir
@@ -204,16 +204,14 @@ module {
       %91 = arith.addi %arg17, %c128 : index
       %92 = arith.cmpi slt, %91, %47 : index
       %93 = tt.broadcast %92 : (i1) -> tensor<128x128xi1, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>
-      %94 = tt.broadcast %92 : (i1) -> tensor<128x128xi1, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>
-      %95 = arith.andi %94, %93 : tensor<128x128xi1, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>
-      %96 = "triton_gpu.copy_async"(%arg15, %93, %cst_1) {cache = 1 : i32, evict = 1 : i32, isVolatile = false} : (tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128xi1, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128xf16, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>) -> tensor<128x128xf16, #triton_gpu<"shared (memory) encoding<>">>
-      %97 = "triton_gpu.copy_async"(%arg16, %95, %cst_1) {cache = 1 : i32, evict = 1 : i32, isVolatile = false} : (tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128xi1, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128xf16, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>) -> tensor<128x128xf16, #triton_gpu<"shared (memory) encoding<>">>
-      %98 = tt.broadcast %c128_i32 : (i32) -> tensor<128x128xi32, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>
-      %99 = tt.getelementptr %arg15, %98, : tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>
-      %100 = arith.muli %arg7, %c128_i32 : i32
-      %101 = tt.broadcast %100 : (i32) -> tensor<128x128xi32, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>
-      %102 = tt.getelementptr %arg16, %101, : tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>
-      scf.yield %85, %87, %90, %96, %97, %99, %102, %91 : tensor<128x128xf32, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128xf16, #triton_gpu<"shared (memory) encoding<>">>, tensor<128x128xf16, #triton_gpu<"shared (memory) encoding<>">>, tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, index
+      %94 = "triton_gpu.copy_async"(%arg15, %93, %cst_1) {cache = 1 : i32, evict = 1 : i32, isVolatile = false} : (tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128xi1, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128xf16, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>) -> tensor<128x128xf16, #triton_gpu<"shared (memory) encoding<>">>
+      %95 = "triton_gpu.copy_async"(%arg16, %93, %cst_1) {cache = 1 : i32, evict = 1 : i32, isVolatile = false} : (tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128xi1, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128xf16, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>) -> tensor<128x128xf16, #triton_gpu<"shared (memory) encoding<>">>
+      %96 = tt.broadcast %c128_i32 : (i32) -> tensor<128x128xi32, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>
+      %97 = tt.getelementptr %arg15, %96, : tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>
+      %98 = arith.muli %arg7, %c128_i32 : i32
+      %99 = tt.broadcast %98 : (i32) -> tensor<128x128xi32, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>
+      %100 = tt.getelementptr %arg16, %99, : tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>
+      scf.yield %85, %87, %90, %94, %95, %97, %100, %91 : tensor<128x128xf32, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128xf16, #triton_gpu<"shared (memory) encoding<>">>, tensor<128x128xf16, #triton_gpu<"shared (memory) encoding<>">>, tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, tensor<128x128x!tt.ptr<f16>, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>, index
     }
     %56 = arith.truncf %55#0 : tensor<128x128xf32, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">> to tensor<128x128xf16, #triton_gpu<"coalesced encoding<threadTileSize = 1, 1, blockTileSize = 32, 1, order = 0, 1>">>
     %57 = arith.muli %12, %c128_i32 : i32