[all-commits] [llvm/llvm-project] 28dd55: [RISCV][GISel] Do libcall for G_FPTOSI, G_FPTOUI w...

[Gábor Spaits via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 28dd55b97372271591d7802fd7b7eede0832aaa9
      https://github.com/llvm/llvm-project/commit/28dd55b97372271591d7802fd7b7eede0832aaa9
  Author: Gábor Spaits <gaborspaits1 at gmail.com>
  Date:   2024-06-07 (Fri, 07 Jun 2024)

  Changed paths:
    M llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp
    A llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-fptoi-rv32-libcall.mir
    A llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-fptoi-rv64-libcall.mir

  Log Message:
  -----------
  [RISCV][GISel] Do libcall for G_FPTOSI, G_FPTOUI when no D or F support (#94613)

When compiling the following code:
```cpp
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <stdbool.h>

int main() {
    int a;
    float f;
    scanf("%d", &a);

    scanf("%f", &f);
    a += (int)f;
    
    return a;
}
``` 
for `-march=rv32ima_zbb` we get a libcall:
```
call    scanf
        lw      a0, -20(s0)
        call    __fixsfsi
        mv      a1, a0
```
When we try to use GlobalISel we get this error:
```
 error in backend: unable to legalize instruction: %9:_(s32) = G_FPTOSI %8:_(s32) (in function: main)
```

(Here is a link to a reproducer in Godblot:
https://godbolt.org/z/f67vEEb41 )

The goal of this PR is to do a libcall for the legalization of
`G_FPTOSI` and `G_FPTOUI` instead of doing a fallback to Selection DAG
to do the same libcall later.



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