[flang-commits] [PATCH] D132154: [flang] Legacy extension intrinsic functions IMAG, IZEXT, JZEXT

[Peter Klausler via Phabricator via flang-commits]

klausler created this revision.
klausler added a reviewer: PeteSteinfeld.
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Support these legacy extension intrinsic functions with unambiguous
semantics in those existing compilers that support them by means
of recognizing them as aliases for standard intrinsics (IMAG) or
with simple rewrites (IZEXT, JZEXT).  Note that ZEXT has different
semantics in different existing compilers, so we will not support it
due to lack of a broad unambiguous precedent.


https://reviews.llvm.org/D132154

Files:
  flang/docs/Extensions.md
  flang/lib/Evaluate/fold-integer.cpp
  flang/lib/Evaluate/intrinsics.cpp
  flang/test/Evaluate/fold-jzext.f90


Index: flang/test/Evaluate/fold-jzext.f90
===================================================================
--- /dev/null
+++ flang/test/Evaluate/fold-jzext.f90
@@ -0,0 +1,10 @@
+! RUN: %python %S/test_folding.py %s %flang_fc1
+! Tests folding of IZEXT() & JZEXT()
+module m
+  logical, parameter :: test_1 = kind(izext(-1_1)) == 2
+  logical, parameter :: test_2 = izext(-1_1) == 255_2
+  logical, parameter :: test_3 = kind(jzext(-1_1)) == 4
+  logical, parameter :: test_4 = jzext(-1_1) == 255_4
+  logical, parameter :: test_5 = kind(jzext(-1_2)) == 4
+  logical, parameter :: test_6 = jzext(-1_2) == 255_4
+end module
Index: flang/lib/Evaluate/intrinsics.cpp
===================================================================
--- flang/lib/Evaluate/intrinsics.cpp
+++ flang/lib/Evaluate/intrinsics.cpp
@@ -507,6 +507,8 @@
         DefaultLogical, Rank::elemental, IntrinsicClass::inquiryFunction},
     {"is_iostat_end", {{"i", AnyInt}}, DefaultLogical},
     {"is_iostat_eor", {{"i", AnyInt}}, DefaultLogical},
+    {"izext", {{"i", AnyInt}}, TypePattern{IntType, KindCode::exactKind, 2}},
+    {"jzext", {{"i", AnyInt}}, DefaultInt},
     {"kind", {{"x", AnyIntrinsic}}, DefaultInt, Rank::elemental,
         IntrinsicClass::inquiryFunction},
     {"lbound",
@@ -844,7 +846,7 @@
 // TODO: Coarray intrinsic functions
 //   LCOBOUND, UCOBOUND, IMAGE_INDEX, COSHAPE
 // TODO: Non-standard intrinsic functions
-//  LSHIFT, RSHIFT, SHIFT, ZEXT, IZEXT,
+//  LSHIFT, RSHIFT, SHIFT,
 //  COMPL, EQV, NEQV, INT8, JINT, JNINT, KNINT,
 //  QCMPLX, QEXT, QFLOAT, QREAL, DNUM,
 //  INUM, JNUM, KNUM, QNUM, RNUM, RAN, RANF, ILEN,
@@ -860,6 +862,7 @@
 // compatibility and builtins.
 static const std::pair<const char *, const char *> genericAlias[]{
     {"and", "iand"},
+    {"imag", "aimag"},
     {"or", "ior"},
     {"xor", "ieor"},
     {"__builtin_ieee_selected_real_kind", "selected_real_kind"},
Index: flang/lib/Evaluate/fold-integer.cpp
===================================================================
--- flang/lib/Evaluate/fold-integer.cpp
+++ flang/lib/Evaluate/fold-integer.cpp
@@ -762,6 +762,17 @@
                 return i.ISHFTC(countVal);
               }));
     }
+  } else if (name == "izext" || name == "jzext") {
+    if (args.size() == 1) {
+      if (auto *expr{UnwrapExpr<Expr<SomeInteger>>(args[0])}) {
+        // Rewrite to IAND(INT(n,k),255_k) for k=KIND(T)
+        intrinsic->name = "iand";
+        auto converted{ConvertToType<T>(std::move(*expr))};
+        *expr = Fold(context, Expr<SomeInteger>{std::move(converted)});
+        args.emplace_back(AsGenericExpr(Expr<T>{Scalar<T>{255}}));
+        return FoldIntrinsicFunction(context, std::move(funcRef));
+      }
+    }
   } else if (name == "lbound") {
     return LBOUND(context, std::move(funcRef));
   } else if (name == "leadz" || name == "trailz" || name == "poppar" ||
Index: flang/docs/Extensions.md
===================================================================
--- flang/docs/Extensions.md
+++ flang/docs/Extensions.md
@@ -235,6 +235,11 @@
   respectively.
 * A digit count of d=0 is accepted in Ew.0, Dw.0, and Gw.0 output
   editing if no nonzero scale factor (kP) is in effect.
+* The name `IMAG` is accepted as an alias for the generic intrinsic
+  function `AIMAG`.
+* The legacy extension intrinsic functions `IZEXT` and `JZEXT`
+  are supported; `ZEXT` has different behavior with various older
+  compilers, so it is not supported.
 
 ### Extensions supported when enabled by options
 


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