[flang/flang-rt] Implement PERROR intrinsic form GNU Extension

Author: JDPailleux

flang-rt/lib/runtime/extensions.cpp

@@ -17,6 +17,7 @@
 #include "flang/Runtime/entry-names.h"
 #include "flang/Runtime/io-api.h"
 #include <chrono>
+#include <cstdio>
 #include <cstring>
 #include <ctime>
 #include <signal.h>
@@ -262,5 +263,8 @@ int RTNAME(Chdir)(const char *name) {
 
 int FORTRAN_PROCEDURE_NAME(ierrno)() { return errno; }
 
+// PERROR(STRING)
+void FORTRAN_PROCEDURE_NAME(perror)(const char *str) { perror(str); }
+
 } // namespace Fortran::runtime
 } // extern "C"

flang/docs/Intrinsics.md

@@ -1106,3 +1106,15 @@ end program chdir_func
 - **Standard:** GNU extension
 - **Class:** function
 - **Syntax:** `RESULT = IERRNO()`
+
+### Non-Standard Intrinsics: PERROR
+
+#### Description
+`PERROR(STRING)` prints (on the C stderr stream) a newline-terminated error message corresponding to the last system error.
+This is prefixed by `STRING`, a colon and a space.
+
+#### Usage and Info
+
+- **Standard:** GNU extension
+- **Class:** subroutine
+- **Syntax:** `CALL PERROR(STRING)`

flang/include/flang/Runtime/extensions.h

@@ -75,5 +75,8 @@ int RTNAME(Chdir)(const char *name);
 // GNU extension function IERRNO()
 int FORTRAN_PROCEDURE_NAME(ierrno)();
 
+// GNU extension subroutine PERROR(STRING)
+void FORTRAN_PROCEDURE_NAME(perror)(const char *str);
+
 } // extern "C"
 #endif // FORTRAN_RUNTIME_EXTENSIONS_H_

flang/test/Lower/Intrinsics/perror.f90

@@ -0,0 +1,14 @@
+! RUN: bbc -emit-fir %s -o - | FileCheck --check-prefixes=CHECK %s
+! RUN: %flang_fc1 -emit-fir %s -o - | FileCheck --check-prefixes=CHECK %s
+
+! CHECK-LABEL: func @_QPtest_perror(
+subroutine test_perror()
+  character(len=10) :: string
+  call perror(string)
+  ! CHECK: %[[C10:.*]] = arith.constant 10 : index
+  ! CHECK: %[[VAL_0:.*]] = fir.alloca !fir.char<1,10> {bindc_name = "string", uniq_name = "_QFtest_perrorEstring"}
+  ! CHECK: %[[VAL_1:.*]] = fir.declare %[[VAL_0]] typeparams %[[C10]] {uniq_name = "_QFtest_perrorEstring"} : (!fir.ref<!fir.char<1,10>>, index) -> !fir.ref<!fir.char<1,10>>
+  ! CHECK: %[[VAL_2:.*]] = fir.emboxchar %[[VAL_1]], %[[C10]] : (!fir.ref<!fir.char<1,10>>, index) -> !fir.boxchar<1>
+  ! CHECK: fir.call @_QPperror(%[[VAL_2]]) fastmath<contract> : (!fir.boxchar<1>) -> () 
+  ! CHECK: return
+end subroutine test_perror