[mlir][llvm] Add is constant intrinsic.

The revision adds LLVM's is constant intrinsic.

Depends on D150643

Reviewed By: Dinistro

Differential Revision: https://reviews.llvm.org/D150660

Author: gysit

mlir/include/mlir/Dialect/LLVMIR/LLVMIntrinsicOps.td

@@ -262,12 +262,17 @@ def LLVM_USubWithOverflowOp : LLVM_ArithWithOverflowOp<"usub.with.overflow">;
 def LLVM_SMulWithOverflowOp : LLVM_ArithWithOverflowOp<"smul.with.overflow">;
 def LLVM_UMulWithOverflowOp : LLVM_ArithWithOverflowOp<"umul.with.overflow">;
 
+//
+// Optimization hint intrinsics.
+//
+
 def LLVM_AssumeOp
   : LLVM_ZeroResultIntrOp<"assume", []>, Arguments<(ins I1:$cond)>;
 
-//
-// Expect intrinsics.
-//
+def LLVM_IsConstantOp : LLVM_IntrOp<"is.constant", [], [0], [Pure], 1> {
+  let arguments = (ins LLVM_Type:$val);
+  let results = (outs I1:$res);
+}
 
 def LLVM_ExpectOp
   : LLVM_OneResultIntrOp<"expect", [], [0],

mlir/test/Target/LLVMIR/Import/intrinsic.ll

@@ -467,6 +467,14 @@ define void @assume(i1 %true) {
   ret void
 }
 
+; CHECK-LABEL: @is_constant
+; CHECK-SAME:  %[[VAL:[a-zA-Z0-9]+]]
+define void @is_constant(i32 %0) {
+  ; CHECK:  "llvm.intr.is.constant"(%[[VAL]]) : (i32) -> i1
+  %2 = call i1 @llvm.is.constant.i32(i32 %0)
+  ret void
+}
+
 ; CHECK-LABEL: @expect
 ; CHECK-SAME:  %[[VAL:[a-zA-Z0-9]+]]
 define void @expect(i32 %0) {
@@ -792,6 +800,7 @@ declare { i32, i1 } @llvm.smul.with.overflow.i32(i32, i32)
 declare { <8 x i32>, <8 x i1> } @llvm.smul.with.overflow.v8i32(<8 x i32>, <8 x i32>)
 declare { i32, i1 } @llvm.umul.with.overflow.i32(i32, i32)
 declare { <8 x i32>, <8 x i1> } @llvm.umul.with.overflow.v8i32(<8 x i32>, <8 x i32>)
+declare i1 @llvm.is.constant.i32(i32)
 declare i32 @llvm.expect.i32(i32, i32)
 declare i16 @llvm.expect.with.probability.i16(i16, i16, double immarg)
 declare token @llvm.coro.id(i32, ptr readnone, ptr nocapture readonly, ptr)

mlir/test/Target/LLVMIR/llvmir-intrinsics.mlir

@@ -466,6 +466,13 @@ llvm.func @umul_with_overflow_test(%arg0: i32, %arg1: i32, %arg2: vector<8xi32>,
   llvm.return
 }
 
+// CHECK-LABEL: @is_constant
+llvm.func @is_constant(%arg0: i32) {
+  // CHECK: call i1 @llvm.is.constant.i32(i32 %{{.*}})
+  %0 = "llvm.intr.is.constant"(%arg0) : (i32) -> i1
+  llvm.return
+}
+
 // CHECK-LABEL: @expect
 llvm.func @expect(%arg0: i32) {
   %0 = llvm.mlir.constant(42 : i32) : i32
@@ -830,6 +837,7 @@ llvm.func @lifetime(%p: !llvm.ptr) {
 // CHECK-DAG: declare { <8 x i32>, <8 x i1> } @llvm.usub.with.overflow.v8i32(<8 x i32>, <8 x i32>)
 // CHECK-DAG: declare { i32, i1 } @llvm.umul.with.overflow.i32(i32, i32)
 // CHECK-DAG: declare { <8 x i32>, <8 x i1> } @llvm.umul.with.overflow.v8i32(<8 x i32>, <8 x i32>)
+// CHECK-DAG: declare i1 @llvm.is.constant.i32(i32)
 // CHECK-DAG: declare i32 @llvm.expect.i32(i32, i32)
 // CHECK-DAG: declare i16 @llvm.expect.with.probability.i16(i16, i16, double immarg)
 // CHECK-DAG: declare token @llvm.coro.id(i32, ptr readnone, ptr nocapture readonly, ptr)