[Mlir-commits] [mlir] [mlir][SPIR-V] Add SPIRVToLLVM conversion for GL.FClamp/SClamp/UClamp (PR #203831)

[Arseniy Obolenskiy]

https://github.com/aobolensk updated https://github.com/llvm/llvm-project/pull/203831

>From 80a6849c7d7da987f19ca9e401d00b1aebbc6d01 Mon Sep 17 00:00:00 2001
From: Arseniy Obolenskiy <arseniy.obolenskiy at amd.com>
Date: Mon, 15 Jun 2026 08:07:27 +0200
Subject: [PATCH 1/2] [mlir][SPIR-V] Add SPIRVToLLVM conversion for
 GL.FClamp/SClamp/UClamp

Lower the GLSL clamp ops as nested min/max following `min(max(x, y), z)`
---
 .../Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp    | 26 ++++++++++++++
 .../SPIRVToLLVM/gl-ops-to-llvm.mlir           | 36 +++++++++++++++++++
 2 files changed, 62 insertions(+)

diff --git a/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp b/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp
index c43415b27b1b3..bc1d690061a91 100644
--- a/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp
+++ b/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp
@@ -921,6 +921,29 @@ class InverseSqrtPattern
   }
 };
 
+/// Converts the GLSL clamp ops (FClamp, SClamp, UClamp) into a nested
+/// min/max sequence, following the op semantics `min(max(x, minVal), maxVal)`.
+template <typename SPIRVOp, typename LLVMMinOp, typename LLVMMaxOp>
+class ClampPattern : public SPIRVToLLVMConversion<SPIRVOp> {
+public:
+  using SPIRVToLLVMConversion<SPIRVOp>::SPIRVToLLVMConversion;
+
+  LogicalResult
+  matchAndRewrite(SPIRVOp op, typename SPIRVOp::Adaptor adaptor,
+                  ConversionPatternRewriter &rewriter) const override {
+    auto dstType = this->getTypeConverter()->convertType(op.getType());
+    if (!dstType)
+      return rewriter.notifyMatchFailure(op, "type conversion failed");
+
+    Location loc = op.getLoc();
+    Value max = LLVMMaxOp::create(rewriter, loc, dstType, adaptor.getX(),
+                                  adaptor.getY());
+    rewriter.template replaceOpWithNewOp<LLVMMinOp>(op, dstType, max,
+                                                    adaptor.getZ());
+    return success();
+  }
+};
+
 /// Converts `spirv.Load` and `spirv.Store` to LLVM dialect.
 template <typename SPIRVOp>
 class LoadStorePattern : public SPIRVToLLVMConversion<SPIRVOp> {
@@ -1897,6 +1920,9 @@ void mlir::populateSPIRVToLLVMConversionPatterns(
       DirectConversionPattern<spirv::GLFAbsOp, LLVM::FAbsOp>,
       DirectConversionPattern<spirv::GLFloorOp, LLVM::FFloorOp>,
       DirectConversionPattern<spirv::GLFmaOp, LLVM::FMAOp>,
+      ClampPattern<spirv::GLFClampOp, LLVM::MinNumOp, LLVM::MaxNumOp>,
+      ClampPattern<spirv::GLSClampOp, LLVM::SMinOp, LLVM::SMaxOp>,
+      ClampPattern<spirv::GLUClampOp, LLVM::UMinOp, LLVM::UMaxOp>,
       DirectConversionPattern<spirv::GLFMaxOp, LLVM::MaxNumOp>,
       DirectConversionPattern<spirv::GLFMinOp, LLVM::MinNumOp>,
       DirectConversionPattern<spirv::GLLogOp, LLVM::LogOp>,
diff --git a/mlir/test/Conversion/SPIRVToLLVM/gl-ops-to-llvm.mlir b/mlir/test/Conversion/SPIRVToLLVM/gl-ops-to-llvm.mlir
index ffa47efbf9213..c23b33c1625cd 100644
--- a/mlir/test/Conversion/SPIRVToLLVM/gl-ops-to-llvm.mlir
+++ b/mlir/test/Conversion/SPIRVToLLVM/gl-ops-to-llvm.mlir
@@ -91,6 +91,18 @@ spirv.func @fmin(%arg0: f32, %arg1: vector<3xf16>) "None" {
   spirv.Return
 }
 
+//===----------------------------------------------------------------------===//
+// spirv.GL.FClamp
+//===----------------------------------------------------------------------===//
+
+// CHECK-LABEL: @fclamp
+spirv.func @fclamp(%arg0: f32, %arg1: f32, %arg2: f32) "None" {
+  // CHECK: %[[MAX:.*]] = llvm.intr.maxnum(%{{.*}}, %{{.*}}) : (f32, f32) -> f32
+  // CHECK: llvm.intr.minnum(%[[MAX]], %{{.*}}) : (f32, f32) -> f32
+  %0 = spirv.GL.FClamp %arg0, %arg1, %arg2 : f32
+  spirv.Return
+}
+
 //===----------------------------------------------------------------------===//
 // spirv.GL.Log
 //===----------------------------------------------------------------------===//
@@ -208,6 +220,30 @@ spirv.func @umin(%arg0: i16, %arg1: vector<3xi32>) "None" {
   spirv.Return
 }
 
+//===----------------------------------------------------------------------===//
+// spirv.GL.SClamp
+//===----------------------------------------------------------------------===//
+
+// CHECK-LABEL: @sclamp
+spirv.func @sclamp(%arg0: i16, %arg1: i16, %arg2: i16) "None" {
+  // CHECK: %[[MAX:.*]] = llvm.intr.smax(%{{.*}}, %{{.*}}) : (i16, i16) -> i16
+  // CHECK: llvm.intr.smin(%[[MAX]], %{{.*}}) : (i16, i16) -> i16
+  %0 = spirv.GL.SClamp %arg0, %arg1, %arg2 : i16
+  spirv.Return
+}
+
+//===----------------------------------------------------------------------===//
+// spirv.GL.UClamp
+//===----------------------------------------------------------------------===//
+
+// CHECK-LABEL: @uclamp
+spirv.func @uclamp(%arg0: i32, %arg1: i32, %arg2: i32) "None" {
+  // CHECK: %[[MAX:.*]] = llvm.intr.umax(%{{.*}}, %{{.*}}) : (i32, i32) -> i32
+  // CHECK: llvm.intr.umin(%[[MAX]], %{{.*}}) : (i32, i32) -> i32
+  %0 = spirv.GL.UClamp %arg0, %arg1, %arg2 : i32
+  spirv.Return
+}
+
 //===----------------------------------------------------------------------===//
 // spirv.GL.Sqrt
 //===----------------------------------------------------------------------===//

>From 030c2466aa092e7183e755f53aeaa2f1f045f07d Mon Sep 17 00:00:00 2001
From: Arseniy Obolenskiy <gooddoog at student.su>
Date: Mon, 6 Jul 2026 11:18:06 +0200
Subject: [PATCH 2/2] Update mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp

Co-authored-by: Igor Wodiany <dev at wodiany.com>
---
 mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp b/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp
index bc1d690061a91..a81922e739232 100644
--- a/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp
+++ b/mlir/lib/Conversion/SPIRVToLLVM/SPIRVToLLVM.cpp
@@ -931,7 +931,7 @@ class ClampPattern : public SPIRVToLLVMConversion<SPIRVOp> {
   LogicalResult
   matchAndRewrite(SPIRVOp op, typename SPIRVOp::Adaptor adaptor,
                   ConversionPatternRewriter &rewriter) const override {
-    auto dstType = this->getTypeConverter()->convertType(op.getType());
+    Type dstType = this->getTypeConverter()->convertType(op.getType());
     if (!dstType)
       return rewriter.notifyMatchFailure(op, "type conversion failed");