[IR] Allow fast math flags on fptrunc and fpext (#115894)

This consists of:
 * Make these instructions part of FPMathOperator.
* Adjust bitcode/ir readers/writers to expect fast math flags on these
instructions.
 * Make IRBuilder set the fast math flags on these instructions.
 * Update langref and release notes.
* Update a bunch of tests. Some of these are due to InstCombineCasts
incorrectly adding fast math flags to fptrunc, which will be fixed in a
later patch.

1 files changed, 10 insertions, 2 deletions

diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index dd72d46..3431149 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -7004,8 +7004,6 @@ int LLParser::parseInstruction(Instruction *&Inst, BasicBlock *BB,
     return false;
   }
   case lltok::kw_sext:
-  case lltok::kw_fptrunc:
-  case lltok::kw_fpext:
   case lltok::kw_bitcast:
   case lltok::kw_addrspacecast:
   case lltok::kw_sitofp:
@@ -7014,6 +7012,16 @@ int LLParser::parseInstruction(Instruction *&Inst, BasicBlock *BB,
   case lltok::kw_inttoptr:
   case lltok::kw_ptrtoint:
     return parseCast(Inst, PFS, KeywordVal);
+  case lltok::kw_fptrunc:
+  case lltok::kw_fpext: {
+    FastMathFlags FMF = EatFastMathFlagsIfPresent();
+    if (parseCast(Inst, PFS, KeywordVal))
+      return true;
+    if (FMF.any())
+      Inst->setFastMathFlags(FMF);
+    return false;
+  }
+
   // Other.
   case lltok::kw_select: {
     FastMathFlags FMF = EatFastMathFlagsIfPresent();