[RISCV] Support .option rvc and norvc assembler directives

These directives allow the 'C' (compressed) extension to be enabled/disabled 
within a single file.

Differential Revision: https://reviews.llvm.org/D45864
Patch by Kito Cheng

llvm-svn: 332107

2 files changed, 30 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/RISCV/option-norvc.ll b/llvm/test/CodeGen/RISCV/option-norvc.ll
new file mode 100644
index 00000000000..381fb37735d
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/option-norvc.ll
@@ -0,0 +1,15 @@
+; RUN: llc -mtriple=riscv32 -mattr=+c  -filetype=obj < %s\
+; RUN: | llvm-objdump -triple=riscv32 -mattr=+c -d -riscv-no-aliases -\
+; RUN: | FileCheck -check-prefix=CHECK %s
+
+; This test demonstrates that .option norvc has no effect on codegen when
+; emitting an ELF directly.
+
+define i32 @add(i32 %a, i32 %b) nounwind {
+; CHECK-LABEL: add:
+; CHECK:    c.add a0, a1
+; CHECK-NEXT:    c.jr ra
+  tail call void asm sideeffect ".option norvc", ""()
+  %add = add nsw i32 %b, %a
+  ret i32 %add
+}
diff --git a/llvm/test/CodeGen/RISCV/option-rvc.ll b/llvm/test/CodeGen/RISCV/option-rvc.ll
new file mode 100644
index 00000000000..3c207bd424f
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/option-rvc.ll
@@ -0,0 +1,15 @@
+; RUN: llc -mtriple=riscv32 -filetype=obj < %s\
+; RUN: | llvm-objdump -triple=riscv32 -mattr=+c -d -riscv-no-aliases -\
+; RUN: | FileCheck -check-prefix=CHECK %s
+
+; This test demonstrates that .option norvc has no effect on codegen when
+; emitting an ELF directly.
+
+define i32 @add(i32 %a, i32 %b) nounwind {
+; CHECK-LABEL: add:
+; CHECK:    add a0, a1, a0
+; CHECK-NEXT:    jalr zero, ra, 0
+  tail call void asm sideeffect ".option rvc", ""()
+  %add = add nsw i32 %b, %a
+  ret i32 %add
+}