[flang-commits] [flang] [flang] Add -O flag to tco (PR #151869)

[via flang-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-flang-driver

Author: None (parabola94)

<details>
<summary>Changes</summary>

At the moment, there is no established way to emit LLVM IR before optimization in LLVM. tco can partially does, but the optimization level is fixed to 2. This patch adds -O flag to tco.

Note that this is not completely equivalent to the frontend option. tco does not accept -O flag without numbers, and the default optimization level is not 0 but 2.

---
Full diff: https://github.com/llvm/llvm-project/pull/151869.diff


2 Files Affected:

- (modified) flang/test/Driver/tco-test-gen.fir (+5-4) 
- (modified) flang/tools/tco/tco.cpp (+33-2) 


``````````diff
diff --git a/flang/test/Driver/tco-test-gen.fir b/flang/test/Driver/tco-test-gen.fir
index 38d4e50ecf3aa..ec566488e32dd 100644
--- a/flang/test/Driver/tco-test-gen.fir
+++ b/flang/test/Driver/tco-test-gen.fir
@@ -1,5 +1,6 @@
 // RUN: tco -emit-final-mlir %s | FileCheck %s --check-prefixes=CHECK,AA,CMPLX
 // RUN: tco -emit-final-mlir -enable-aa=false %s | FileCheck %s --check-prefixes=CHECK,NOAA,CMPLX
+// RUN: tco -emit-final-mlir -O0 -enable-aa %s | FileCheck %s --check-prefixes=CHECK,NOAA,CMPLX
 // RUN: tco -emit-final-mlir -simplify-mlir %s | FileCheck %s --check-prefixes=CHECK,AA,SIMPLE
 // RUN: tco -emit-final-mlir -enable-aa=false -simplify-mlir %s | FileCheck %s --check-prefixes=CHECK,NOAA,SIMPLE
 // RUN: tco -test-gen %s | FileCheck %s --check-prefixes=CHECK,NOAA,SIMPLE
@@ -37,10 +38,10 @@ func.func @_QPtest(%arg0: !fir.ref<i32> {fir.bindc_name = "num"}, %arg1: !fir.re
 }
 
 // CHECK-LABEL:   llvm.func @_QPtest(
-// CHECK-SAME:      %[[ARG0:.*]]: !llvm.ptr {fir.bindc_name = "num", llvm.nocapture},
-// CHECK-SAME:      %[[ARG1:.*]]: !llvm.ptr {fir.bindc_name = "lb", llvm.nocapture},
-// CHECK-SAME:      %[[ARG2:.*]]: !llvm.ptr {fir.bindc_name = "ub", llvm.nocapture},
-// CHECK-SAME:      %[[ARG3:.*]]: !llvm.ptr {fir.bindc_name = "step", llvm.nocapture}) {
+// CHECK-SAME:      %[[ARG0:.*]]: !llvm.ptr {fir.bindc_name = "num"{{[^}]*}}},
+// CHECK-SAME:      %[[ARG1:.*]]: !llvm.ptr {fir.bindc_name = "lb"{{[^}]*}}},
+// CHECK-SAME:      %[[ARG2:.*]]: !llvm.ptr {fir.bindc_name = "ub"{{[^}]*}}},
+// CHECK-SAME:      %[[ARG3:.*]]: !llvm.ptr {fir.bindc_name = "step"{{[^}]*}}}) {
 
 // CMPLX:           %[[VAL_0:.*]] = llvm.mlir.constant(1 : i64) : i64
 // CMPLX:           %[[VAL_1:.*]] = llvm.alloca %[[VAL_0]] x i32 {bindc_name = "i"} : (i64) -> !llvm.ptr
diff --git a/flang/tools/tco/tco.cpp b/flang/tools/tco/tco.cpp
index d8daf8769cb21..b6d7c142c19df 100644
--- a/flang/tools/tco/tco.cpp
+++ b/flang/tools/tco/tco.cpp
@@ -51,6 +51,12 @@ static cl::opt<bool> emitFir("emit-fir",
                              cl::desc("Parse and pretty-print the input"),
                              cl::init(false));
 
+static cl::opt<unsigned>
+    OptLevel("O",
+             cl::desc("Optimization level. [-O0, -O1, -O2, or -O3] "
+                      "(default = '-O2')"),
+             cl::Prefix, cl::init(2));
+
 static cl::opt<std::string> targetTriple("target",
                                          cl::desc("specify a target triple"),
                                          cl::init("native"));
@@ -96,6 +102,22 @@ static void printModule(mlir::ModuleOp mod, raw_ostream &output) {
   output << mod << '\n';
 }
 
+static std::optional<llvm::OptimizationLevel>
+getOptimizationLevel(unsigned level) {
+  switch (level) {
+  default:
+    return std::nullopt;
+  case 0:
+    return llvm::OptimizationLevel::O0;
+  case 1:
+    return llvm::OptimizationLevel::O1;
+  case 2:
+    return llvm::OptimizationLevel::O2;
+  case 3:
+    return llvm::OptimizationLevel::O3;
+  }
+}
+
 // compile a .fir file
 static llvm::LogicalResult
 compileFIR(const mlir::PassPipelineCLParser &passPipeline) {
@@ -157,9 +179,18 @@ compileFIR(const mlir::PassPipelineCLParser &passPipeline) {
     if (mlir::failed(passPipeline.addToPipeline(pm, errorHandler)))
       return mlir::failure();
   } else {
-    MLIRToLLVMPassPipelineConfig config(llvm::OptimizationLevel::O2);
+    std::optional<llvm::OptimizationLevel> level =
+        getOptimizationLevel(OptLevel);
+    if (!level) {
+      errs() << "Error invalid optimization level\n";
+      return mlir::failure();
+    }
+    MLIRToLLVMPassPipelineConfig config(*level);
+    // TODO: config.StackArrays should be set here?
     config.EnableOpenMP = true;  // assume the input contains OpenMP
-    config.AliasAnalysis = enableAliasAnalysis && !testGeneratorMode;
+    config.AliasAnalysis =
+        OptLevel > 0 && enableAliasAnalysis && !testGeneratorMode;
+    config.LoopVersioning = OptLevel > 2;
     if (codeGenLLVM) {
       // Run only CodeGen passes.
       fir::createDefaultFIRCodeGenPassPipeline(pm, config);

``````````

</details>


https://github.com/llvm/llvm-project/pull/151869