[RISCV] Hard float ABI support

The RISC-V hard float calling convention requires the frontend to:

* Detect cases where, once "flattened", a struct can be passed using
int+fp or fp+fp registers under the hard float ABI and coerce to the
appropriate type(s) * Track usage of GPRs and FPRs in order to gate the
above, and to
determine when signext/zeroext attributes must be added to integer
scalars

This patch attempts to do this in compliance with the documented ABI,
and uses ABIArgInfo::CoerceAndExpand in order to do this. @rjmccall, as
author of that code I've tagged you as reviewer for initial feedback on
my usage.

Note that a previous version of the ABI indicated that when passing an
int+fp struct using a GPR+FPR, the int would need to be sign or
zero-extended appropriately. GCC never did this and the ABI was changed,
which makes life easier as ABIArgInfo::CoerceAndExpand can't currently
handle sign/zero-extension attributes.

Differential Revision: https://reviews.llvm.org/D60456

llvm-svn: 366450

1 files changed, 11 insertions, 2 deletions

diff --git a/clang/lib/Basic/Targets/RISCV.cpp b/clang/lib/Basic/Targets/RISCV.cpp
index f800bb0b25d..58272d14abd 100644
--- a/clang/lib/Basic/Targets/RISCV.cpp
+++ b/clang/lib/Basic/Targets/RISCV.cpp
@@ -65,9 +65,18 @@ void RISCVTargetInfo::getTargetDefines(const LangOptions &Opts,
   Builder.defineMacro("__riscv");
   bool Is64Bit = getTriple().getArch() == llvm::Triple::riscv64;
   Builder.defineMacro("__riscv_xlen", Is64Bit ? "64" : "32");
-  // TODO: modify when more code models and ABIs are supported.
+  // TODO: modify when more code models are supported.
   Builder.defineMacro("__riscv_cmodel_medlow");
-  Builder.defineMacro("__riscv_float_abi_soft");
+
+  StringRef ABIName = getABI();
+  if (ABIName == "ilp32f" || ABIName == "lp64f")
+    Builder.defineMacro("__riscv_float_abi_single");
+  else if (ABIName == "ilp32d" || ABIName == "lp64d")
+    Builder.defineMacro("__riscv_float_abi_double");
+  else if (ABIName == "ilp32e")
+    Builder.defineMacro("__riscv_abi_rve");
+  else
+    Builder.defineMacro("__riscv_float_abi_soft");
 
   if (HasM) {
     Builder.defineMacro("__riscv_mul");