[Nios2] final infrastructure addition to provide compilation of simple return from a function.

[AndreiGrischenko]

Summary

Hi,

Please review next patch for Nios2 code-gen.

This huge patch includes all missing functionality needed to provide first compilation of a program that simply returns from a function.
I've added a test case that checks for "ret" instruction printed in assembly output.

Next patches will be smaller. They will bring Nios2 R1, R2 ISA, instruction lowering and etc.

Thanks!

[craig.topper]

lib/Target/Nios2/CMakeLists.txt

22 ↗

(On Diff #121739)

Frame lowering should be above InstrInfo.cpp to be in alphabetical ordering

lib/Target/Nios2/InstPrinter/Nios2InstPrinter.cpp

29 ↗

(On Diff #121739)

Are your register names not lowercase in the td file?

Though it seems several targets do this.

lib/Target/Nios2/MCTargetDesc/CMakeLists.txt

2 ↗

(On Diff #121739)

Can you put these on one line per file and alphabetize?

lib/Target/Nios2/MCTargetDesc/Nios2MCTargetDesc.cpp

51

The if at line 49 check if CPU is empty or generic. There's no way to get here and the CPU be "nios2r2"

[AndreiGrischenko]

Updates according to Craig's comments.

lib/Target/Nios2/CMakeLists.txt

22 ↗

(On Diff #121739)

OK

lib/Target/Nios2/InstPrinter/Nios2InstPrinter.cpp

29 ↗

(On Diff #121739)

Yes, right, thanks. It is not necessary for Nios2 as all registers are in lowercase.

lib/Target/Nios2/MCTargetDesc/CMakeLists.txt

2 ↗

(On Diff #121739)

OK

lib/Target/Nios2/MCTargetDesc/Nios2MCTargetDesc.cpp

51

Yes, I reworked this routine.

[craig.topper]

lib/Target/Nios2/MCTargetDesc/Nios2MCTargetDesc.cpp

49

That's a comparison not an assignment.

[echristo]

lib/Target/Nios2/MCTargetDesc/Nios2MCTargetDesc.cpp

49

Which also means an untested code path - relatedly, there are no tests here.

[AndreiGrischenko]

lib/Target/Nios2/MCTargetDesc/Nios2MCTargetDesc.cpp

49

omg! Very stupid typo.

49

Not exactly. This patch is aimed to start printing "ret" into assembly output, so I've added appropriate test case for that. Further I plan to add more test cases when adding exact things, not just infrastructure.
However I will add one more test checking that Nios2 processors are accepted.

[AndreiGrischenko]

lib/Target/Nios2/MCTargetDesc/Nios2MCTargetDesc.cpp

49

Current patch does not provide enough functionality to check that CPU=empty is incorrect.

[AndreiGrischenko]

Fixed a typo when assigning default CPU for Nios2.
Added a test checking for acceptance of Nios2 processors.

[AndreiGrischenko]

Hi Craig,

Thanks for acceptance the patch. Unfortunately a person who makes commits declined the patch because formally only small part of it was accepted.
Now I update diffs again to bring the whole patch again as unified diff(with changes regarding your comments). Could you please accept it again?
Sorry for that.

Thanks,
Andrei.

[craig.topper]

LGTM other than the one comment. Please fix before you commit.

[craig.topper]

lib/Target/Nios2/Nios2RegisterInfo.cpp

39 ↗

(On Diff #125080)

This should be MCPhysReg not uint16_t.

[AndreiGrischenko]

lib/Target/Nios2/Nios2RegisterInfo.cpp

39 ↗

(On Diff #125080)

OK, I will fix it before the commit.

lib/Target/Nios2/MCTargetDesc/Nios2MCTargetDesc.cpp

static MCRegisterInfo *createNios2MCRegisterInfo(const Triple &TT) {
   MCRegisterInfo *X = new MCRegisterInfo();
   InitNios2MCRegisterInfo(X, Nios2::R15); // defined in Nios2GenRegisterInfo.inc
   return X;
 }
 
 static MCSubtargetInfo *
 createNios2MCSubtargetInfo(const Triple &TT, StringRef CPU, StringRef FS) {
   if (CPU.empty() || CPU == "generic") {
-    CPU == "nios2r1";
+    CPU = "nios2r1";
   }
 
   return createNios2MCSubtargetInfoImpl(TT, CPU, FS);
   // createNios2MCSubtargetInfoImpl defined in Nios2GenSubtargetInfo.inc
 }
 
 static MCAsmInfo *createNios2MCAsmInfo(const MCRegisterInfo &MRI,
                                        const Triple &TT) {
   MCAsmInfo *MAI = new Nios2MCAsmInfo(TT);
 

test/CodeGen/Nios2/proc_support.ll

+; This tests that llc accepts Nios2 processors.
+
+; RUN: not not llc < %s -asm-verbose=false -march=nios2 -mcpu=nios2r1 2>&1 | FileCheck %s --check-prefix=ARCH
+; RUN: not not llc < %s -asm-verbose=false -march=nios2 -mcpu=nios2r2 2>&1 | FileCheck %s --check-prefix=ARCH
+
+; ARCH-NOT: is not a recognized processor
+
+define i32 @f(i32 %i) {
+  ret i32 %i
+}

test/CodeGen/Nios2/ret_generated.ll

-; This tests that llc accepts Nios2 target.
+; This tests that llc generates 'ret' instruction in assembly output.
 
 ; RUN: llc < %s -march=nios2 2>&1 | FileCheck %s --check-prefix=ARCH
 
 ; ARCH: ret
 
 define i32 @f(i32 %i) {
   ret i32 %i
 }