[RISCV] Implement RISCV ABI lowering

RISCVABIInfo is implemented in terms of XLen, supporting both RV32 and RV64. 
Unfortunately we need to count argument registers in the frontend in order to 
determine when to emit signext and zeroext attributes. Integer scalars are 
extended according to their type up to 32-bits and then sign-extended to XLen 
when passed in registers, but are anyext when passed on the stack. This patch 
only implements the base integer (soft float) ABIs.

For more information on the RISC-V ABI, see [the ABI 
doc](https://github.com/riscv/riscv-elf-psabi-doc/blob/master/riscv-elf.md), 
my [golden model](https://github.com/lowRISC/riscv-calling-conv-model), and 
the [LLVM RISC-V calling convention 
patch](https://reviews.llvm.org/D39898#2d1595b4) (specifically the comment 
documenting frontend expectations).

Differential Revision: https://reviews.llvm.org/D40023

llvm-svn: 322494

1 files changed, 47 insertions, 0 deletions

diff --git a/clang/test/Driver/riscv32-toolchain.c b/clang/test/Driver/riscv32-toolchain.c
index efe550e0f29..3839f8e59c9 100644
--- a/clang/test/Driver/riscv32-toolchain.c
+++ b/clang/test/Driver/riscv32-toolchain.c
@@ -73,3 +73,50 @@ int align_ld = __alignof(long double);
 
 // CHECK: @align_vl = global i32 4
 int align_vl = __alignof(va_list);
+
+// Check types
+
+// CHECK: zeroext i8 @check_char()
+char check_char() { return 0; }
+
+// CHECK: define signext i16 @check_short()
+short check_short() { return 0; }
+
+// CHECK: define i32 @check_int()
+int check_int() { return 0; }
+
+// CHECK: define i32 @check_wchar_t()
+int check_wchar_t() { return 0; }
+
+// CHECK: define i32 @check_long()
+long check_long() { return 0; }
+
+// CHECK: define i64 @check_longlong()
+long long check_longlong() { return 0; }
+
+// CHECK: define zeroext i8 @check_uchar()
+unsigned char check_uchar() { return 0; }
+
+// CHECK: define zeroext i16 @check_ushort()
+unsigned short check_ushort() { return 0; }
+
+// CHECK: define i32 @check_uint()
+unsigned int check_uint() { return 0; }
+
+// CHECK: define i32 @check_ulong()
+unsigned long check_ulong() { return 0; }
+
+// CHECK: define i64 @check_ulonglong()
+unsigned long long check_ulonglong() { return 0; }
+
+// CHECK: define i32 @check_size_t()
+size_t check_size_t() { return 0; }
+
+// CHECK: define float @check_float()
+float check_float() { return 0; }
+
+// CHECK: define double @check_double()
+double check_double() { return 0; }
+
+// CHECK: define fp128 @check_longdouble()
+long double check_longdouble() { return 0; }