[flang][fir] Add fir.if -> scf.if and add filecheck test file #142938

StarryCSF · 2025-06-05T10:06:15Z

This commmit is a supplement for #140374.
RFC:https://discourse.llvm.org/t/rfc-add-fir-affine-optimization-fir-pass-pipeline/86190/6

github-actions · 2025-06-05T10:06:38Z

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llvmbot · 2025-06-05T10:07:19Z

@llvm/pr-subscribers-flang-fir-hlfir

Author: Q (StarryCSF)

Changes

This commmit is a supplement for #140374.
RFC:https://discourse.llvm.org/t/rfc-add-fir-affine-optimization-fir-pass-pipeline/86190/6

Full diff: https://github.com/llvm/llvm-project/pull/142938.diff

2 Files Affected:

(modified) flang/lib/Optimizer/Transforms/FIRToSCF.cpp (+56-2)
(added) flang/test/Fir/FirToSCF/if.fir (+97)

diff --git a/flang/lib/Optimizer/Transforms/FIRToSCF.cpp b/flang/lib/Optimizer/Transforms/FIRToSCF.cpp
index f06ad2db90d55..fa9bba39016b9 100644
--- a/flang/lib/Optimizer/Transforms/FIRToSCF.cpp
+++ b/flang/lib/Optimizer/Transforms/FIRToSCF.cpp
@@ -87,13 +87,67 @@ struct DoLoopConversion : public OpRewritePattern<fir::DoLoopOp> {
     return success();
   }
 };
+
+struct IfConversion : public OpRewritePattern<fir::IfOp> {
+  using OpRewritePattern<fir::IfOp>::OpRewritePattern;
+  LogicalResult matchAndRewrite(fir::IfOp ifOp,
+                                PatternRewriter &rewriter) const override {
+    auto loc = ifOp.getLoc();
+    auto condition = ifOp.getCondition();
+    auto resultTypes = ifOp.getResultTypes();
+    bool hasResult = !resultTypes.empty();
+    auto scfIfOp = rewriter.create<scf::IfOp>(loc, resultTypes, condition,
+                                              !ifOp.getElseRegion().empty());
+	// then region
+    assert(!ifOp.getThenRegion().empty() && "must have then region");
+    auto &firThenBlock = ifOp.getThenRegion().front();
+    auto &scfThenBlock = scfIfOp.getThenRegion().front();
+    auto &firThenOps = firThenBlock.getOperations();
+    auto *firThenTerminator = firThenBlock.getTerminator();
+
+    rewriter.setInsertionPointToStart(&scfThenBlock);
+    // not splice terminator
+    scfThenBlock.getOperations().splice(scfThenBlock.begin(), firThenOps,
+                                        firThenOps.begin(),
+                                        std::prev(firThenOps.end()));
+    // create terminator scf.yield
+    if (hasResult) {
+      rewriter.setInsertionPointToEnd(&scfThenBlock);
+      auto thenResults = firThenTerminator->getOperands();
+      rewriter.create<scf::YieldOp>(firThenTerminator->getLoc(), thenResults);
+    }
+
+    // else region
+    if (!ifOp.getElseRegion().empty()) {
+      auto &firElseBlock = ifOp.getElseRegion().front();
+      auto &scfElseBlock = scfIfOp.getElseRegion().front();
+      auto &firElseOps = firElseBlock.getOperations();
+      auto *firElseTerminator = firElseBlock.getTerminator();
+
+      rewriter.setInsertionPointToStart(&scfElseBlock);
+      scfElseBlock.getOperations().splice(scfElseBlock.begin(), firElseOps,
+                                          firElseOps.begin(),
+                                          std::prev(firElseOps.end()));
+
+      if (hasResult) {
+        rewriter.setInsertionPointToEnd(&scfElseBlock);
+        auto elseResults = firElseTerminator->getOperands();
+        rewriter.create<scf::YieldOp>(firElseTerminator->getLoc(), elseResults);
+      }
+    }
+
+    scfIfOp->setAttrs(ifOp->getAttrs());
+    rewriter.replaceOp(ifOp, scfIfOp);
+    return success();
+  }
+};
 } // namespace
 
 void FIRToSCFPass::runOnOperation() {
   RewritePatternSet patterns(&getContext());
-  patterns.add<DoLoopConversion>(patterns.getContext());
+  patterns.add<DoLoopConversion, IfConversion>(patterns.getContext());
   ConversionTarget target(getContext());
-  target.addIllegalOp<fir::DoLoopOp>();
+  target.addIllegalOp<fir::DoLoopOp, fir::IfOp>();
   target.markUnknownOpDynamicallyLegal([](Operation *) { return true; });
   if (failed(
           applyPartialConversion(getOperation(), target, std::move(patterns))))
diff --git a/flang/test/Fir/FirToSCF/if.fir b/flang/test/Fir/FirToSCF/if.fir
new file mode 100644
index 0000000000000..8885b0343095d
--- /dev/null
+++ b/flang/test/Fir/FirToSCF/if.fir
@@ -0,0 +1,97 @@
+
+// RUN: fir-opt %s --fir-to-scf | FileCheck %s
+
+// CHECK: func.func @_QFPtest_only(
+// CHECK:   %[[ARG0:.*]]: !fir.ref<tuple<!fir.ref<f32>>>) {
+// CHECK:   %[[VAL_0:.*]] = arith.constant 1 : i32
+// CHECK:   %[[VAL_1:.*]] = arith.constant false
+// CHECK:   %[[VAL_2:.*]] = arith.constant 0 : i32
+// CHECK:   scf.if %[[VAL_1:.*]] {
+// CHECK:    %[[VAL_3:.*]] = arith.addi %[[VAL_2:.*]], %[[VAL_0:.*]] : i32
+// CHECK:   }
+// CHECK:   return
+// CHECK:   }
+func.func @_QFPtest_only(%arg0: !fir.ref<tuple<!fir.ref<f32>>>) {
+    %c1_i32 = arith.constant 1 : i32
+    %false = arith.constant false
+    %c0_i32 = arith.constant 0 : i32
+    fir.if %false {
+      %0 = arith.addi %c0_i32, %c1_i32 : i32
+    }
+    return
+  }
+
+// CHECK: func.func @_QFPtest_else(
+// CHECK:   %[[ARG0:.*]]: !fir.ref<tuple<!fir.ref<f32>>>) {
+// CHECK:   %[[VAL_0:.*]] = arith.constant 1 : i32
+// CHECK:   %[[VAL_1:.*]] = arith.constant false
+// CHECK:   %[[VAL_2:.*]] = arith.constant 0 : i32
+// CHECK:   %[[VAL_3:.*]] = fir.dummy_scope : !fir.dscope
+// CHECK:   %[[VAL_4:.*]] = fir.coordinate_of %[[ARG0:.*]], %[[VAL_2:.*]] : (!fir.ref<tuple<!fir.ref<f32>>>, i32) -> !fir.llvm_ptr<!fir.ref<f32>>
+// CHECK:   %[[VAL_5:.*]] = fir.load %[[VAL_4:.*]] : !fir.llvm_ptr<!fir.ref<f32>>
+// CHECK:   %[[VAL_6:.*]] = fir.declare %[[VAL_5:.*]] {fortran_attrs = #fir.var_attrs<host_assoc>, uniq_name = "_QFEx"} : (!fir.ref<f32>) -> !fir.ref<f32>
+// CHECK:   %[[VAL_7:.*]] = fir.address_of(@_QFFtest_elseEsum) : !fir.ref<i32>
+// CHECK:   %[[VAL_10:.*]] = fir.declare %[[VAL_7:.*]] {uniq_name = "_QFFtest_elseEsum"} : (!fir.ref<i32>) -> !fir.ref<i32>
+// CHECK:   scf.if %[[VAL_1:.*]] {
+// CHECK:     %[[VAL_8:.*]] = fir.load %[[VAL_10:.*]] : !fir.ref<i32>
+// CHECK:     %[[VAL_9:.*]] = arith.addi %[[VAL_8:.*]], %[[VAL_0:.*]] : i32
+// CHECK:     fir.store %[[VAL_9:.*]] to %[[VAL_10:.*]] : !fir.ref<i32>
+// CHECK:   } else {
+// CHECK:     %[[VAL_8:.*]] = fir.load %[[VAL_10:.*]] : !fir.ref<i32>
+// CHECK:     %[[VAL_9:.*]] = arith.addi %[[VAL_8:.*]], %c1_i32 : i32
+// CHECK:     fir.store %[[VAL_9:.*]] to %[[VAL_10:.*]] : !fir.ref<i32>
+// CHECK:   }
+// CHECK:   return
+// CHECK: }
+func.func  @_QFPtest_else(%arg0: !fir.ref<tuple<!fir.ref<f32>>> {}) attributes {} {
+  %c1_i32 = arith.constant 1 : i32
+  %false = arith.constant false
+  %c0_i32 = arith.constant 0 : i32
+  %0 = fir.dummy_scope : !fir.dscope
+  %1 = fir.coordinate_of %arg0, %c0_i32 : (!fir.ref<tuple<!fir.ref<f32>>>, i32) -> !fir.llvm_ptr<!fir.ref<f32>>
+  %2 = fir.load %1 : !fir.llvm_ptr<!fir.ref<f32>>
+  %3 = fir.declare %2 {fortran_attrs = #fir.var_attrs<host_assoc>, uniq_name = "_QFEx"} : (!fir.ref<f32>) -> !fir.ref<f32>
+  %4 = fir.address_of(@_QFFtest_elseEsum) : !fir.ref<i32>
+  %5 = fir.declare %4 {uniq_name = "_QFFtest_elseEsum"} : (!fir.ref<i32>) -> !fir.ref<i32>
+  fir.if %false {
+    %6 = fir.load %5 : !fir.ref<i32>
+    %7 = arith.addi %6, %c1_i32 : i32
+    fir.store %7 to %5 : !fir.ref<i32>
+  } else {
+    %6 = fir.load %5 : !fir.ref<i32>
+    %7 = arith.addi %6, %c1_i32 : i32
+    fir.store %7 to %5 : !fir.ref<i32>
+  }
+  return
+}
+
+// CHECK-LABEL:     func.func @test_two_result() {
+// CHECK:           %[[VAL_0:.*]] = arith.constant 10 : i32
+// CHECK:           %[[VAL_1:.*]] = arith.constant 5 : i32
+// CHECK:           %[[VAL_2:.*]] = arith.cmpi sgt, %[[VAL_0:.*]], %[[VAL_1:.*]] : i32
+// CHECK:           %[[VAL_3:.*]] = arith.constant 3.140000e+00 : f32
+// CHECK:           %[[VAL_4:.*]] = arith.constant 2.710000e+00 : f32
+// CHECK:           %[[VAL_5:.*]] = arith.constant 1.000000e+00 : f32
+// CHECK:           %[[VAL_6:.*]] = arith.constant 2.000000e+00 : f32
+// CHECK:           %[[RES:[0-9]+]]:2 = scf.if %[[VAL_2:.*]] -> (f32, f32) {
+// CHECK:            scf.yield %[[VAL_3:.*]], %[[VAL_4:.*]] : f32, f32
+// CHECK:            } else {
+// CHECK:              scf.yield %[[VAL_5:.*]], %[[VAL_6:.*]] : f32, f32
+// CHECK:            }
+// CHECK:            return 
+// CHECK:            }
+func.func @test_two_result() {
+  %c10_i32 = arith.constant 10 : i32
+  %c5_i32 = arith.constant 5 : i32
+  %cmp = arith.cmpi sgt, %c10_i32, %c5_i32 : i32
+  %c3_14_f32 = arith.constant 3.14 : f32
+  %c2_71_f32 = arith.constant 2.71 : f32
+  %c1_0_f32 = arith.constant 1.0 : f32
+  %c2_0_f32 = arith.constant 2.0 : f32
+  %x, %y = fir.if %cmp -> (f32, f32) {
+    fir.result %c3_14_f32, %c2_71_f32 : f32, f32
+  } else {
+    fir.result %c1_0_f32, %c2_0_f32 : f32, f32
+  }
+  return
+}

github-actions · 2025-06-05T12:20:53Z

⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️

You can test this locally with the following command:

git-clang-format --diff HEAD~1 HEAD --extensions cpp -- flang/lib/Optimizer/Transforms/FIRToSCF.cpp

View the diff from clang-format here.

diff --git a/flang/lib/Optimizer/Transforms/FIRToSCF.cpp b/flang/lib/Optimizer/Transforms/FIRToSCF.cpp
index fa9bba390..efa0a808d 100644
--- a/flang/lib/Optimizer/Transforms/FIRToSCF.cpp
+++ b/flang/lib/Optimizer/Transforms/FIRToSCF.cpp
@@ -98,7 +98,7 @@ struct IfConversion : public OpRewritePattern<fir::IfOp> {
     bool hasResult = !resultTypes.empty();
     auto scfIfOp = rewriter.create<scf::IfOp>(loc, resultTypes, condition,
                                               !ifOp.getElseRegion().empty());
-	// then region
+    // then region
     assert(!ifOp.getThenRegion().empty() && "must have then region");
     auto &firThenBlock = ifOp.getThenRegion().front();
     auto &scfThenBlock = scfIfOp.getThenRegion().front();

tblah

Other than the nit comment, this LGTM. Thanks

tblah · 2025-06-05T12:21:28Z

flang/lib/Optimizer/Transforms/FIRToSCF.cpp

+  using OpRewritePattern<fir::IfOp>::OpRewritePattern;
+  LogicalResult matchAndRewrite(fir::IfOp ifOp,
+                                PatternRewriter &rewriter) const override {
+    auto loc = ifOp.getLoc();


Please could you only use auto when the type is written in the initialization expression (or in a few fringe cases where the type is an unreliable implementation detail). For example

This is okay because scf::IfOp is made very clear by the expression

auto scfIfOp = rewriter.create<scf::IfOp>(...);

This would be better with mlir::Location spelled out

auto loc = ifOp.getLoc();

OK,Thanks for reviewing the code.Re-submit a pull request later to resolve this .

llvmbot added flang Flang issues not falling into any other category flang:fir-hlfir labels Jun 5, 2025

tblah approved these changes Jun 5, 2025

View reviewed changes

StarryCSF closed this Jun 5, 2025

StarryCSF force-pushed the main branch from 2d01c7d to 6da8f3b Compare June 5, 2025 13:40

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[flang][fir] Add fir.if -> scf.if and add filecheck test file #142938

[flang][fir] Add fir.if -> scf.if and add filecheck test file #142938

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[flang][fir] Add fir.if -> scf.if and add filecheck test file #142938

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