Add helper functions to query properties of the lowered Target (#8192)

Makefile

@@ -594,6 +594,7 @@ SOURCE_FILES = \
   StripAsserts.cpp \
   Substitute.cpp \
   Target.cpp \
+  TargetQueryOps.cpp \
   Tracing.cpp \
   TrimNoOps.cpp \
   Tuple.cpp \
@@ -778,6 +779,7 @@ HEADER_FILES = \
   StripAsserts.h \
   Substitute.h \
   Target.h \
+  TargetQueryOps.h \
   Tracing.h \
   TrimNoOps.h \
   Tuple.h \

src/CMakeLists.txt

@@ -160,6 +160,7 @@ set(HEADER_FILES
     StripAsserts.h
     Substitute.h
     Target.h
+    TargetQueryOps.h
     Tracing.h
     TrimNoOps.h
     Tuple.h
@@ -346,6 +347,7 @@ set(SOURCE_FILES
     StripAsserts.cpp
     Substitute.cpp
     Target.cpp
+    TargetQueryOps.cpp
     Tracing.cpp
     TrimNoOps.cpp
     Tuple.cpp

src/IR.cpp

@@ -680,6 +680,11 @@ const char *const intrinsic_op_names[] = {
     "sorted_avg",
     "strict_float",
     "stringify",
+    "target_arch_is",
+    "target_bits",
+    "target_has_feature",
+    "target_natural_vector_size",
+    "target_os_is",
     "undef",
     "unreachable",
     "unsafe_promise_clamped",

src/IR.h

@@ -612,6 +612,13 @@ struct Call : public ExprNode<Call> {
         sorted_avg,
         strict_float,
         stringify,
+
+        target_arch_is,
+        target_bits,
+        target_has_feature,
+        target_natural_vector_size,
+        target_os_is,
+
         undef,
         unreachable,
         unsafe_promise_clamped,

src/IROperator.cpp

@@ -2735,4 +2735,24 @@ Expr concat_bits(const std::vector<Expr> &e) {
     return Call::make(t.with_bits(t.bits() * (int)e.size()), Call::concat_bits, e, Call::Intrinsic);
 }
 
+Expr target_arch_is(Target::Arch arch) {
+    return Call::make(Bool(), Call::target_arch_is, {Expr((int)arch)}, Call::PureIntrinsic);
+}
+
+Expr target_os_is(Target::OS os) {
+    return Call::make(Bool(), Call::target_os_is, {Expr((int)os)}, Call::PureIntrinsic);
+}
+
+Expr target_bits() {
+    return Call::make(Int(32), Call::target_bits, {}, Call::PureIntrinsic);
+}
+
+Expr target_has_feature(Target::Feature feat) {
+    return Call::make(Bool(), Call::target_has_feature, {Expr((int)feat)}, Call::PureIntrinsic);
+}
+
+Expr target_natural_vector_size(Type t) {
+    return Call::make(Int(32), Call::target_natural_vector_size, {make_zero(t.element_of())}, Call::PureIntrinsic);
+}
+
 }  // namespace Halide

src/IROperator.h

@@ -11,6 +11,7 @@
 #include <map>
 
 #include "Expr.h"
+#include "Target.h"
 #include "Tuple.h"
 
 namespace Halide {
@@ -1689,6 +1690,46 @@ Expr rounding_mul_shift_right(Expr a, Expr b, Expr q);
 Expr rounding_mul_shift_right(Expr a, Expr b, int q);
 //@}
 
+/** Return a boolean Expr for the corresponding field of the Target
+ * being used during lowering; they can be useful in writing library
+ * code without having to plumb a Target through call sites, so that you
+ * can do things like
+ \code
+    Expr e = select(target_arch_is(Target::ARM), something, something_else);
+ \endcode
+ */
+//@{
+Expr target_arch_is(Target::Arch arch);
+Expr target_os_is(Target::OS os);
+Expr target_has_feature(Target::Feature feat);
+//@}
+
+/** Return the bit width of the Target used during lowering; this can be useful
+ * in writing library code without having to plumb a Target through call sites, so that you
+ * can do things like
+ \code
+    Expr e = select(target_bits() == 32, something, something_else);
+ \endcode
+ */
+Expr target_bits();
+
+/** Return the natural vector width for the given Type for the Target
+ * being used during lowering; this can be useful in writing library
+ * code without having to plumb a Target through call sites, so that you
+ * can do things like
+ \code
+    f.vectorize(x, target_natural_vector_size(Float(32)));
+ \endcode
+ */
+//@{
+Expr target_natural_vector_size(Type t);
+template<typename data_t>
+Expr target_natural_vector_size() {
+    return target_natural_vector_size(type_of<data_t>());
+}
+//@}
+
+
 }  // namespace Halide
 
 #endif

src/Lower.cpp

@@ -70,6 +70,7 @@
 #include "StrictifyFloat.h"
 #include "StripAsserts.h"
 #include "Substitute.h"
+#include "TargetQueryOps.h"
 #include "Tracing.h"
 #include "TrimNoOps.h"
 #include "UnifyDuplicateLets.h"
@@ -144,6 +145,8 @@ void lower_impl(const vector<Function> &output_funcs,
     // Create a deep-copy of the entire graph of Funcs.
     auto [outputs, env] = deep_copy(output_funcs, build_environment(output_funcs));
 
+    lower_target_query_ops(env, t);
+
     bool any_strict_float = strictify_float(env, t);
     result_module.set_any_strict_float(any_strict_float);
 

src/TargetQueryOps.cpp

@@ -0,0 +1,54 @@
+#include "TargetQueryOps.h"
+
+#include "Function.h"
+#include "IRMutator.h"
+#include "IROperator.h"
+
+namespace Halide {
+namespace Internal {
+
+namespace {
+
+class LowerTargetQueryOps : public IRMutator {
+    const Target &t;
+
+    using IRMutator::visit;
+
+    Expr visit(const Call *call) override {
+        if (call->is_intrinsic(Call::target_arch_is)) {
+            Target::Arch arch = (Target::Arch)*as_const_int(call->args[0]);
+            return make_bool(t.arch == arch);
+        } else if (call->is_intrinsic(Call::target_has_feature)) {
+            Target::Feature feat = (Target::Feature)*as_const_int(call->args[0]);
+            return make_bool(t.has_feature(feat));
+        } else if (call->is_intrinsic(Call::target_natural_vector_size)) {
+            Expr zero = call->args[0];
+            return Expr(t.natural_vector_size(zero.type()));
+        } else if (call->is_intrinsic(Call::target_os_is)) {
+            Target::OS os = (Target::OS)*as_const_int(call->args[0]);
+            return make_bool(t.os == os);
+        } else if (call->is_intrinsic(Call::target_bits)) {
+            return Expr(t.bits);
+        }
+
+        return IRMutator::visit(call);
+    }
+
+public:
+    LowerTargetQueryOps(const Target &t)
+        : t(t) {
+    }
+};
+
+}  // namespace
+
+void lower_target_query_ops(std::map<std::string, Function> &env, const Target &t) {
+    for (auto &iter : env) {
+        Function &func = iter.second;
+        LowerTargetQueryOps ltqo(t);
+        func.mutate(&ltqo);
+    }
+}
+
+}  // namespace Internal
+}  // namespace Halide

src/TargetQueryOps.h

@@ -0,0 +1,24 @@
+#ifndef HALIDE_TARGET_QUERY_OPS_H
+#define HALIDE_TARGET_QUERY_OPS_H
+
+/** \file
+ * Defines a lowering pass to lower all target_is() and target_has() helpers.
+ */
+
+#include <map>
+#include <string>
+
+namespace Halide {
+
+struct Target;
+
+namespace Internal {
+
+class Function;
+
+void lower_target_query_ops(std::map<std::string, Function> &env, const Target &t);
+
+}  // namespace Internal
+}  // namespace Halide
+
+#endif

test/correctness/CMakeLists.txt

@@ -311,6 +311,7 @@ tests(GROUPS correctness
       strict_float_bounds.cpp
       strided_load.cpp
       target.cpp
+      target_query.cpp
       tiled_matmul.cpp
       tracing.cpp
       tracing_bounds.cpp

test/correctness/target_query.cpp

@@ -0,0 +1,48 @@
+#include "Halide.h"
+#include <stdio.h>
+
+using namespace Halide;
+
+int main(int argc, char **argv) {
+    // For simplicity, only run this test on hosts that we can predict.
+    Target t = get_host_target();
+    if (t.arch != Target::X86 || t.bits != 64 || t.os != Target::OSX) {
+        printf("[SKIP] This test only runs on x86-64-osx.\n");
+        return 0;
+    }
+
+    t = t.with_feature(Target::Debug);
+
+    // Full specification round-trip, crazy features
+    Target t1 = Target(Target::OSX, Target::X86, 64,
+                       {Target::CUDA, Target::Debug});
+
+    Expr is_arm = target_arch_is(Target::ARM);
+    Expr is_x86 = target_arch_is(Target::X86);
+    Expr bits = target_bits();
+    Expr is_android = target_os_is(Target::Android);
+    Expr is_osx = target_os_is(Target::OSX);
+    Expr vec = target_natural_vector_size<float>();
+    Expr has_cuda = target_has_feature(Target::CUDA);
+    Expr has_vulkan = target_has_feature(Target::Vulkan);
+
+    Func f;
+    Var x;
+
+    f(x) = select(is_arm, 1, 0) +
+           select(is_x86, 2, 0) +
+           select(vec == 4, 4, 0) +
+           select(is_android, 8, 0) +
+           select(is_osx, 16, 0) +
+           select(bits == 32, 32, 0) +
+           select(bits == 64, 64, 0) +
+           select(has_cuda, 128, 0) +
+           select(has_vulkan, 256, 0);
+
+    Buffer<int> result = f.realize({1}, t1);
+
+    assert(result(0) == 2 + 4 + 16 + 64 + 128);
+
+    printf("Success!\n");
+    return 0;
+}