[cfe-dev] Question about Clang codegen tests

Sat Nov 27 04:12:24 PST 2021

Hi,

Thanks to all folks that help me, but I'm still a little confused when running `llvm-project/llvm/utils/update_cc_test_checks.py` script. I didn't open a new thread but replied to you directly, hope you won't mind :-)

First of all, the file I want to update: `llvm-project/clang/test/CodeGen/builtins-elementwise-math.c`, has RUN command like: 

`// RUN: %clang_cc1 -triple x86_64-apple-darwin %s -emit-llvm -disable-llvm-passes -o - | FileCheck %s`. 

I found that I cannot generate `CHECKS` unless I remove `-triple x86_64-apple-darwin`. It even cleaned `CHECKS` it used to have. FYI, I'm running Ubuntu in my machine.

Another thing that bothers me is that though I successfully generate `CHECKS`, they are very wired...

I expect:

```

void test_builtin_elementwise_abs(float f1, float f2, double d1, double d2,

                                  float4 vf1, float4 vf2, si8 vi1, si8 vi2,

                                  long long int i1, long long int i2, short si) {

  // CHECK-LABEL: define void @test_builtin_elementwise_abs(

  // CHECK:      [[F1:%.+]] = load float, float* %f1.addr, align 4

  // CHECK-NEXT:  call float @llvm.fabs.f32(float [[F1]])

  f2 = __builtin_elementwise_abs(f1);

  // CHECK:      [[D1:%.+]] = load double, double* %d1.addr, align 8

  // CHECK-NEXT: call double @llvm.fabs.f64(double [[D1]])

  d2 = __builtin_elementwise_abs(d1);

...

```

However, it was like:

```

// CHECK-NEXT:    [[CONV:%.*]] = sext i16 [[TMP8]] to i32

// CHECK-NEXT:    [[ELT_ABS8:%.*]] = call i32 @llvm.abs.i32(i32 [[CONV]], i1 false)

// CHECK-NEXT:    [[CONV9:%.*]] = trunc i32 [[ELT_ABS8]] to i16

// CHECK-NEXT:    store i16 [[CONV9]], i16* [[SI_ADDR]], align 2

// CHECK-NEXT:    ret void

//

void test_builtin_elementwise_abs(float f1, float f2, double d1, double d2,

                                  float4 vf1, float4 vf2, si8 vi1, si8 vi2,

                                  long long int i1, long long int i2, short si) {

  f2 = __builtin_elementwise_abs(f1);

  d2 = __builtin_elementwise_abs(d1);

  vf2 = __builtin_elementwise_abs(vf1);

```

The comments are all above the function declaration, which is not what I want. 

The command to update check result is :

```

python3 ~/dev/cpp-projects/llvm-project/llvm/utils/update_cc_test_checks.py --llvm-bin=/home/jun/dev/cpp-projects/llvm-project/build/bin CodeGen/builtins-elementwise-math.c

```

Best regards,

Jun Zhang

---- 在 星期四, 25 十一月 2021 19:02:48 +0800 Diogo Sampaio <dsampaio at kalray.eu> 撰写 ----

Hi,

see if this helps you tu understand the test it self: https://llvm.org/docs/CommandGuide/FileCheck.html

And once you have a C/C++ input test file with a RUN: command on it, the test commands to check the result usually can be generated with the llvm-project/llvm/utils/update_cc_test_checks.py script.

cheers

Diogo Sampaio
 Senior Compiler Engineer • Kalray
mailto:dsampaio at kalrayinc.com • https://www.kalrayinc.com

https://www.kalrayinc.com

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From: "cfe-dev" <mailto:cfe-dev at lists.llvm.org>
To: "cfe-dev" <mailto:cfe-dev at lists.llvm.org>
Sent: Thursday, November 25, 2021 11:54:27 AM
Subject: [cfe-dev] Question about Clang codegen tests

Hello, everyone!

I'm a newcomer, and want to make some contributions to the LLVM community. Is here the right place to reach out for help? Please forgive me if I did things wrong, as I'm unfamiliar with the LLVM workflow :-) 

So a few days ago I noticed an issue in the bugzilla: https://bugs.llvm.org/show_bug.cgi?id=52444, I thought it would be suitable for me to work on. But now I run into some problems:

* What is meaning of the capitalized words in tests comments?

For example,  in `llvm-project/clang/test/CodeGen/builtins-elementwise-math.c`:

```

// RUN: %clang_cc1 -triple x86_64-apple-darwin %s -emit-llvm -disable-llvm-passes -o - | FileCheck %s

// CHECK-LABEL: define void @test_builtin_elementwise_abs( 

// CHECK:      [[F1:%.+]] = load float, float* %f1.addr, align 4 

// CHECK-NEXT:  call float @llvm.fabs.f32(float [[F1]])

```

What do `RUN`, `CHECK` mean? I can guess they are some test instructions, so I briefly look through the docs, but I can't find anything useful :-( I'm sorry but the docs are so much, it's hard to find something I actually don't know what is.

* How can I write my own test for codegen?

The actual code part is not that hard, problems came in when I want to write some tests. The fact is that I'm unfamiliar with LLVM IR, so I don't know how to write the expected output...

Thanks so much for people who offer me help!

Best regards,

Jun Zhang

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