[AArch64][SVE] Asm: Add parsing/printing support for exact FP immediates.

Some instructions require of a limited set of FP immediates as operands,
for example '#0.5 or #1.0' for SVE's FADD instruction.

This patch adds support for parsing and printing such FP immediates as
exact values (e.g. #0.499999 is not accepted for #0.5).

Reviewers: rengolin, fhahn, SjoerdMeijer, samparker, javed.absar

Reviewed By: SjoerdMeijer

Differential Revision: https://reviews.llvm.org/D47711

llvm-svn: 334826

1 files changed, 10 insertions, 0 deletions

diff --git a/llvm/lib/Target/AArch64/InstPrinter/AArch64InstPrinter.cpp b/llvm/lib/Target/AArch64/InstPrinter/AArch64InstPrinter.cpp
index 3d52fa142ec..8f4fca71800 100644
--- a/llvm/lib/Target/AArch64/InstPrinter/AArch64InstPrinter.cpp
+++ b/llvm/lib/Target/AArch64/InstPrinter/AArch64InstPrinter.cpp
@@ -1517,3 +1517,13 @@ void AArch64InstPrinter::printZPRasFPR(const MCInst *MI, unsigned OpNum,
   unsigned Reg = MI->getOperand(OpNum).getReg();
   O << getRegisterName(Reg - AArch64::Z0 + Base);
 }
+
+template <unsigned ImmIs0, unsigned ImmIs1>
+void AArch64InstPrinter::printExactFPImm(const MCInst *MI, unsigned OpNum,
+                                         const MCSubtargetInfo &STI,
+                                         raw_ostream  &O) {
+  auto *Imm0Desc = AArch64ExactFPImm::lookupExactFPImmByEnum(ImmIs0);
+  auto *Imm1Desc = AArch64ExactFPImm::lookupExactFPImmByEnum(ImmIs1);
+  unsigned Val = MI->getOperand(OpNum).getImm();
+  O << "#" << (Val ? Imm1Desc->Repr : Imm0Desc->Repr);
+}