[RISCV] Add tests for overflow intrinsics

[rogfer01]

Summary

This is using the existing codegen so we can see the change once we custom lower ISD::{U,S}{ADD,SUB}O nodes.

[asb]

Thanks! Looks good to me, but two minor suggestions:

• arith-with-overflow.ll might be a better name
• Add the nounwind attribute to the function definitions, so we still get clean assembly output when cfi directives are emitted.

[rogfer01]

Thanks for the review @asb !

Updated the diff with your suggestions.

[rogfer01]

Oops, I forgot to add the Differential URL in the commit.

Submitted in rL335023: [RISCV] Add tests for overflow intrinsics

test/CodeGen/RISCV/arith-with-overflow.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=riscv32 -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefix=RV32I %s
+
+declare {i32, i1} @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
+declare {i32, i1} @llvm.ssub.with.overflow.i32(i32 %a, i32 %b)
+declare {i32, i1} @llvm.uadd.with.overflow.i32(i32 %a, i32 %b)
+declare {i32, i1} @llvm.usub.with.overflow.i32(i32 %a, i32 %b)
+
+define i1 @sadd(i32 %a, i32 %b, i32* %c) nounwind {
+; RV32I-LABEL: sadd:
+; RV32I:       # %bb.0: # %entry
+; RV32I-NEXT:    add a3, a0, a1
+; RV32I-NEXT:    sw a3, 0(a2)
+; RV32I-NEXT:    addi a2, zero, -1
+; RV32I-NEXT:    slt a1, a2, a1
+; RV32I-NEXT:    slt a0, a2, a0
+; RV32I-NEXT:    slt a2, a2, a3
+; RV32I-NEXT:    xor a2, a0, a2
+; RV32I-NEXT:    xor a0, a0, a1
+; RV32I-NEXT:    seqz a0, a0
+; RV32I-NEXT:    snez a1, a2
+; RV32I-NEXT:    and a0, a0, a1
+; RV32I-NEXT:    ret
+entry:
+  %x = call {i32, i1} @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
+  %calc = extractvalue {i32, i1} %x, 0
+  %ovf = extractvalue {i32, i1} %x, 1
+  store i32 %calc, i32* %c
+  ret i1 %ovf
+}
+
+define i1 @ssub(i32 %a, i32 %b, i32* %c) nounwind {
+; RV32I-LABEL: ssub:
+; RV32I:       # %bb.0: # %entry
+; RV32I-NEXT:    sub a3, a0, a1
+; RV32I-NEXT:    sw a3, 0(a2)
+; RV32I-NEXT:    addi a2, zero, -1
+; RV32I-NEXT:    slt a1, a2, a1
+; RV32I-NEXT:    slt a0, a2, a0
+; RV32I-NEXT:    slt a2, a2, a3
+; RV32I-NEXT:    xor a2, a0, a2
+; RV32I-NEXT:    xor a0, a0, a1
+; RV32I-NEXT:    snez a0, a0
+; RV32I-NEXT:    snez a1, a2
+; RV32I-NEXT:    and a0, a0, a1
+; RV32I-NEXT:    ret
+entry:
+  %x = call {i32, i1} @llvm.ssub.with.overflow.i32(i32 %a, i32 %b)
+  %calc = extractvalue {i32, i1} %x, 0
+  %ovf = extractvalue {i32, i1} %x, 1
+  store i32 %calc, i32* %c
+  ret i1 %ovf
+}
+
+define i1 @uadd(i32 %a, i32 %b, i32* %c) nounwind {
+; RV32I-LABEL: uadd:
+; RV32I:       # %bb.0: # %entry
+; RV32I-NEXT:    add a1, a0, a1
+; RV32I-NEXT:    sw a1, 0(a2)
+; RV32I-NEXT:    sltu a0, a1, a0
+; RV32I-NEXT:    ret
+entry:
+  %x = call {i32, i1} @llvm.uadd.with.overflow.i32(i32 %a, i32 %b)
+  %calc = extractvalue {i32, i1} %x, 0
+  %ovf = extractvalue {i32, i1} %x, 1
+  store i32 %calc, i32* %c
+  ret i1 %ovf
+}
+
+define i1 @usub(i32 %a, i32 %b, i32* %c) nounwind {
+; RV32I-LABEL: usub:
+; RV32I:       # %bb.0: # %entry
+; RV32I-NEXT:    sub a1, a0, a1
+; RV32I-NEXT:    sw a1, 0(a2)
+; RV32I-NEXT:    sltu a0, a0, a1
+; RV32I-NEXT:    ret
+entry:
+  %x = call {i32, i1} @llvm.usub.with.overflow.i32(i32 %a, i32 %b)
+  %calc = extractvalue {i32, i1} %x, 0
+  %ovf = extractvalue {i32, i1} %x, 1
+  store i32 %calc, i32* %c
+  ret i1 %ovf
+}