[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.

Re-landed after backing out 366450 due to missed hunks.

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

llvm-svn: 366480

1 files changed, 2 insertions, 4 deletions

diff --git a/clang/lib/Basic/Targets/RISCV.h b/clang/lib/Basic/Targets/RISCV.h
index bc814b79ce5..ce193feaeb9 100644
--- a/clang/lib/Basic/Targets/RISCV.h
+++ b/clang/lib/Basic/Targets/RISCV.h
@@ -87,8 +87,7 @@ public:
   }
 
   bool setABI(const std::string &Name) override {
-    // TODO: support ilp32f and ilp32d ABIs.
-    if (Name == "ilp32") {
+    if (Name == "ilp32" || Name == "ilp32f" || Name == "ilp32d") {
       ABI = Name;
       return true;
     }
@@ -105,8 +104,7 @@ public:
   }
 
   bool setABI(const std::string &Name) override {
-    // TODO: support lp64f and lp64d ABIs.
-    if (Name == "lp64") {
+    if (Name == "lp64" || Name == "lp64f" || Name == "lp64d") {
       ABI = Name;
       return true;
     }