[flang-commits] [PATCH] D134970: [flang] Do not resolve TRIM/REPEAT length to its argument length

[Jean Perier via Phabricator via flang-commits]

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For TRIM and REPEAT calls, semantics was creating ProcedureDesignators
using the length parameter of the arguments. This caused bugs when
folding LEN(TRIM(char_explicit_constant_length)). The same did not
appeared in folding for REPEAT because it is rewritten at a higher
level to LEN(c)*N.

This is not only a folding issue since any place (like lowering) may
try to use the bad length parameter from the created ProcedureDesignator.

Update intrinsic resolution to not copy the length parameter for TRIM
and REPEAT.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D134970

Files:
  flang/lib/Evaluate/intrinsics.cpp
  flang/test/Evaluate/rewrite01.f90


Index: flang/test/Evaluate/rewrite01.f90
===================================================================
--- flang/test/Evaluate/rewrite01.f90
+++ flang/test/Evaluate/rewrite01.f90
@@ -112,6 +112,7 @@
   external d
   integer, intent(in) :: n, m
   character(n), intent(in) :: e
+  character(5), parameter :: cparam = "abc  "
   interface
      function fun1(L)
        character(L) :: fun1
@@ -155,6 +156,14 @@
   print *, len(fun1(n-m))
   !CHECK: PRINT *, len(mofun(m+1_4))
   print *, len(mofun(m+1))
+  !CHECK: PRINT *, 3_4
+  print *, len(trim(cparam))
+  !CHECK: PRINT *, len(trim(c))
+  print *, len(trim(c))
+  !CHECK: PRINT *, 40_4
+  print *, len(repeat(c, 4))
+  !CHECK: PRINT *, len(repeat(c,int(i,kind=8)))
+  print *, len(repeat(c, i))
 end subroutine len_test
 
 !CHECK-LABEL: associate_tests
Index: flang/lib/Evaluate/intrinsics.cpp
===================================================================
--- flang/lib/Evaluate/intrinsics.cpp
+++ flang/lib/Evaluate/intrinsics.cpp
@@ -78,7 +78,11 @@
     defaultRealKind, // is also the default COMPLEX kind
     doublePrecision, defaultCharKind, defaultLogicalKind,
     any, // matches any kind value; each instance is independent
-    same, // match any kind, but all "same" kinds must be equal
+    // match any kind, but all "same" kinds must be equal. For characters, also
+    // implies that lengths must be equal.
+    same,
+    // for character results, take "same" argument kind but not length
+    sameKindButNotLength,
     operand, // match any kind, with promotion (non-standard)
     typeless, // BOZ literals are INTEGER with this kind
     teamType, // TEAM_TYPE from module ISO_FORTRAN_ENV (for coarrays)
@@ -149,6 +153,8 @@
 static constexpr TypePattern SameFloating{FloatingType, KindCode::same};
 static constexpr TypePattern SameNumeric{NumericType, KindCode::same};
 static constexpr TypePattern SameChar{CharType, KindCode::same};
+static constexpr TypePattern SameCharNewLen{
+    CharType, KindCode::sameKindButNotLength};
 static constexpr TypePattern SameLogical{LogicalType, KindCode::same};
 static constexpr TypePattern SameRelatable{RelatableType, KindCode::same};
 static constexpr TypePattern SameIntrinsic{IntrinsicType, KindCode::same};
@@ -702,7 +708,7 @@
             {"ordered", AnyLogical, Rank::scalar, Optionality::optional}},
         SameType, Rank::scalar, IntrinsicClass::transformationalFunction},
     {"repeat", {{"string", SameChar, Rank::scalar}, {"ncopies", AnyInt}},
-        SameChar, Rank::scalar, IntrinsicClass::transformationalFunction},
+        SameCharNewLen, Rank::scalar, IntrinsicClass::transformationalFunction},
     {"reshape",
         {{"source", SameType, Rank::array}, {"shape", AnyInt, Rank::shape},
             {"pad", SameType, Rank::array, Optionality::optional},
@@ -799,7 +805,7 @@
         SameType, Rank::vector, IntrinsicClass::transformationalFunction},
     {"transpose", {{"matrix", SameType, Rank::matrix}}, SameType, Rank::matrix,
         IntrinsicClass::transformationalFunction},
-    {"trim", {{"string", SameChar, Rank::scalar}}, SameChar, Rank::scalar,
+    {"trim", {{"string", SameChar, Rank::scalar}}, SameCharNewLen, Rank::scalar,
         IntrinsicClass::transformationalFunction},
     {"ubound",
         {{"array", AnyData, Rank::anyOrAssumedRank}, RequiredDIM,
@@ -1784,6 +1790,12 @@
         }
       }
       break;
+    case KindCode::sameKindButNotLength:
+      CHECK(sameArg);
+      if (std::optional<DynamicType> aType{sameArg->GetType()}) {
+        resultType = DynamicType{*category, aType->kind()};
+      }
+      break;
     case KindCode::operand:
       CHECK(operandArg);
       resultType = operandArg->GetType();


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