[flang-commits] [PATCH] D136901: [flang] Speed up folding of LEN_TRIM()

[Peter Klausler via Phabricator via flang-commits]

klausler created this revision.
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LEN_TRIM's folding is currently based on VERIFY(), and it is kind of
slow for the very large CHARACTER arguments that can show up in artificial
test suites.  Rewrite in terms of single-character accesses.


https://reviews.llvm.org/D136901

Files:
  flang/lib/Evaluate/character.h


Index: flang/lib/Evaluate/character.h
===================================================================
--- flang/lib/Evaluate/character.h
+++ flang/lib/Evaluate/character.h
@@ -94,7 +94,13 @@
   }
 
   static ConstantSubscript LEN_TRIM(const Character &str) {
-    return VERIFY(str, Character{' '}, true);
+    auto j{str.length()};
+    for (; j >= 1; --j) {
+      if (str[j - 1] != ' ') {
+        break;
+      }
+    }
+    return static_cast<ConstantSubscript>(j);
   }
 
   static Character REPEAT(const Character &str, ConstantSubscript ncopies) {


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