[Flang][OpenMP] Use fir.if instead of scf.if in lastprivate lowering

For finding the last iteration of a loop, or the last section an
if condition is generated. Using scf::if can cause some lowering
issues since the code contained inside it can have branches. Using
fir::if instead ensures that the fir::if is lowered into branches
along with any code contained inside that can generate branches.

Fixes #62458.

Reviewed By: NimishMishra

Differential Revision: https://reviews.llvm.org/D149547

Author: kiranchandramohan

flang/lib/Lower/OpenMP.cpp

@@ -23,7 +23,6 @@
 #include "flang/Parser/parse-tree.h"
 #include "flang/Semantics/tools.h"
 #include "mlir/Dialect/OpenMP/OpenMPDialect.h"
-#include "mlir/Dialect/SCF/IR/SCF.h"
 #include "llvm/Frontend/OpenMP/OMPConstants.h"
 
 using namespace mlir;
@@ -222,20 +221,20 @@ void DataSharingProcessor::insertLastPrivateCompare(mlir::Operation *op) {
           //  omp.section {
           //      fir.allocate for `private`/`firstprivate`
           //      <More operations here>
-          //      scf.if %true {
+          //      fir.if %true {
           //          ^%lpv_update_blk
           //      }
           //  }
           // }
           //
           // To keep code consistency while handling privatization
-          // through this control flow, add a `scf.if` operation
+          // through this control flow, add a `fir.if` operation
           // that always evaluates to true, in order to create
           // a dedicated sub-region in `omp.section` where
           // lastprivate FIR can reside. Later canonicalizations
           // will optimize away this operation.
 
-          mlir::scf::IfOp ifOp = firOpBuilder.create<mlir::scf::IfOp>(
+          auto ifOp = firOpBuilder.create<fir::IfOp>(
               op->getLoc(),
               firOpBuilder.createIntegerConstant(
                   op->getLoc(), firOpBuilder.getIntegerType(1), 0x1),
@@ -280,7 +279,7 @@ void DataSharingProcessor::insertLastPrivateCompare(mlir::Operation *op) {
         // omp.wsloop {            ...
         //    ...                  store
         //    store       ===>     %cmp = llvm.icmp "eq" %iv %ub
-        //    omp.yield            scf.if %cmp {
+        //    omp.yield            fir.if %cmp {
         // }                         ^%lpv_update_blk:
         //                         }
         //                         omp.yield
@@ -295,8 +294,8 @@ void DataSharingProcessor::insertLastPrivateCompare(mlir::Operation *op) {
               op->getRegion(0).front().getArguments()[0],
               mlir::dyn_cast<mlir::omp::WsLoopOp>(op).getUpperBound()[0]);
         }
-        mlir::scf::IfOp ifOp = firOpBuilder.create<mlir::scf::IfOp>(
-            op->getLoc(), cmpOp, /*else*/ false);
+        auto ifOp =
+            firOpBuilder.create<fir::IfOp>(op->getLoc(), cmpOp, /*else*/ false);
         firOpBuilder.setInsertionPointToStart(&ifOp.getThenRegion().front());
         lastPrivIP = firOpBuilder.saveInsertionPoint();
       } else {

flang/test/Lower/OpenMP/parallel-lastprivate-clause-scalar.f90

@@ -25,7 +25,7 @@
 
 ! Testing last iteration check
 !CHECK-NEXT: %[[IV_CMP:.*]] = arith.cmpi eq, %[[INDX_WS]]
-!CHECK: scf.if %[[IV_CMP]] {
+!CHECK: fir.if %[[IV_CMP]] {
 
 ! Testing lastprivate val update
 !CHECK-DAG: %[[CVT:.*]] = fir.convert %[[ARG1_REF]] : (!fir.ref<!fir.char<1,5>>) -> !fir.ref<i8>
@@ -53,7 +53,7 @@ subroutine lastprivate_character(arg1)
 
 ! Testing last iteration check
 !CHECK-DAG: %[[IV_CMP:.*]] = arith.cmpi eq, %[[INDX_WS]]
-!CHECK-DAG: scf.if %[[IV_CMP]] {
+!CHECK-DAG: fir.if %[[IV_CMP]] {
 
 ! Testing lastprivate val update
 !CHECK-NEXT: %[[CLONE_LD:.*]] = fir.load %[[CLONE]] : !fir.ref<i32>
@@ -82,7 +82,7 @@ subroutine lastprivate_int(arg1)
 
 ! Testing last iteration check
 !CHECK: %[[IV_CMP1:.*]] = arith.cmpi eq, %[[INDX_WS]]
-!CHECK-NEXT: scf.if %[[IV_CMP1]] {
+!CHECK-NEXT: fir.if %[[IV_CMP1]] {
 ! Testing lastprivate val update
 !CHECK-DAG: %[[CLONE_LD1:.*]] = fir.load %[[CLONE1]] : !fir.ref<i32>
 !CHECK-DAG: fir.store %[[CLONE_LD1]] to %[[ARG1]] : !fir.ref<i32>
@@ -113,7 +113,7 @@ subroutine mult_lastprivate_int(arg1, arg2)
 
 !Testing last iteration check
 !CHECK: %[[IV_CMP1:.*]] = arith.cmpi eq, %[[INDX_WS]]
-!CHECK-NEXT: scf.if %[[IV_CMP1]] {
+!CHECK-NEXT: fir.if %[[IV_CMP1]] {
 !Testing lastprivate val update
 !CHECK-DAG: %[[CLONE_LD2:.*]] = fir.load %[[CLONE2]] : !fir.ref<i32>
 !CHECK-DAG: fir.store %[[CLONE_LD2]] to %[[ARG2]] : !fir.ref<i32>
@@ -149,7 +149,7 @@ subroutine mult_lastprivate_int2(arg1, arg2)
 
 ! Testing last iteration check
 !CHECK: %[[IV_CMP1:.*]] = arith.cmpi eq, %[[INDX_WS]]
-!CHECK-NEXT: scf.if %[[IV_CMP1]] {
+!CHECK-NEXT: fir.if %[[IV_CMP1]] {
 ! Testing lastprivate val update
 !CHECK-NEXT: %[[CLONE_LD:.*]] = fir.load %[[CLONE2]] : !fir.ref<i32>
 !CHECK-NEXT: fir.store %[[CLONE_LD]] to %[[ARG2]] : !fir.ref<i32>
@@ -180,7 +180,7 @@ subroutine firstpriv_lastpriv_int(arg1, arg2)
 !CHECK: omp.wsloop for (%[[INDX_WS:.*]]) : {{.*}} {
 ! Testing last iteration check
 !CHECK: %[[IV_CMP1:.*]] = arith.cmpi eq, %[[INDX_WS]]
-!CHECK-NEXT: scf.if %[[IV_CMP1]] {
+!CHECK-NEXT: fir.if %[[IV_CMP1]] {
 ! Testing lastprivate val update
 !CHECK-NEXT: %[[CLONE_LD:.*]] = fir.load %[[CLONE1]] : !fir.ref<i32>
 !CHECK-NEXT: fir.store %[[CLONE_LD]] to %[[ARG1]] : !fir.ref<i32>

flang/test/Lower/OpenMP/sections.f90

@@ -131,7 +131,7 @@ subroutine lastprivate()
 !CHECK: %[[const:.*]] = arith.constant 1 : i32
 !CHECK: %[[result:.*]] = arith.addi %[[temp]], %[[const]] : i32
 !CHECK: fir.store %[[result]] to %[[PRIVATE_X]] : !fir.ref<i32>
-!CHECK: scf.if %[[true]] {
+!CHECK: fir.if %[[true]] {
 !CHECK: %[[temp:.*]] = fir.load %[[PRIVATE_X]] : !fir.ref<i32>
 !CHECK: fir.store %[[temp]] to %[[X]] : !fir.ref<i32>
 !CHECK: }
@@ -168,7 +168,7 @@ subroutine lastprivate()
 !CHECK: %[[const:.*]] = arith.constant 1 : i32
 !CHECK: %[[result:.*]] = arith.addi %[[temp]], %[[const]] : i32
 !CHECK: fir.store %[[result]] to %[[PRIVATE_X]] : !fir.ref<i32>
-!CHECK: scf.if %true {
+!CHECK: fir.if %true {
 !CHECK: %[[temp:.*]] = fir.load %[[PRIVATE_X]] : !fir.ref<i32>
 !CHECK: fir.store %[[temp]] to %[[X]] : !fir.ref<i32>
 !CHECK: }
@@ -205,7 +205,7 @@ subroutine lastprivate()
 !CHECK: %[[const:.*]] = arith.constant 1 : i32
 !CHECK: %[[result:.*]] = arith.addi %[[temp]], %[[const]] : i32
 !CHECK: fir.store %[[result]] to %[[PRIVATE_X]] : !fir.ref<i32>
-!CHECK: scf.if %true {
+!CHECK: fir.if %true {
 !CHECK: %[[temp:.*]] = fir.load %[[PRIVATE_X]] : !fir.ref<i32>
 !CHECK: fir.store %[[temp]] to %[[X]] : !fir.ref<i32>
 !CHECK: omp.barrier