[llvm] [RISCV][GISel] Do libcall for G_FPTOSI, G_FPTOUI when no D or F support (PR #94613)

Gábor Spaits via llvm-commits llvm-commits at lists.llvm.org
Thu Jun 6 06:08:31 PDT 2024


https://github.com/spaits created https://github.com/llvm/llvm-project/pull/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.

>From 22620a93faea804db2b5db0c212a1363bed566df Mon Sep 17 00:00:00 2001
From: Gabor Spaits <gaborspaits1 at gmail.com>
Date: Thu, 6 Jun 2024 14:59:06 +0200
Subject: [PATCH] [RISCV][GISel] Do libcall for G_FPTOSI, G_FPTOUI when d or f
 extensions are not supported

---
 .../Target/RISCV/GISel/RISCVLegalizerInfo.cpp |   3 +-
 .../legalizer/legalize-fptoi-rv32-libcall.mir | 194 ++++++++++++++++++
 2 files changed, 196 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-fptoi-rv32-libcall.mir

diff --git a/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp b/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp
index dbfcab7233bf8..69a139957ff23 100644
--- a/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp
+++ b/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp
@@ -409,7 +409,8 @@ RISCVLegalizerInfo::RISCVLegalizerInfo(const RISCVSubtarget &ST)
   getActionDefinitionsBuilder({G_FPTOSI, G_FPTOUI})
       .legalIf(all(typeInSet(0, {s32, sXLen}), typeIsScalarFPArith(1, ST)))
       .widenScalarToNextPow2(0)
-      .clampScalar(0, s32, sXLen);
+      .clampScalar(0, s32, sXLen)
+      .libcallFor({s32, s32});
 
   getActionDefinitionsBuilder({G_SITOFP, G_UITOFP})
       .legalIf(all(typeIsScalarFPArith(0, ST), typeInSet(1, {s32, sXLen})))
diff --git a/llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-fptoi-rv32-libcall.mir b/llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-fptoi-rv32-libcall.mir
new file mode 100644
index 0000000000000..b22338d521a46
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-fptoi-rv32-libcall.mir
@@ -0,0 +1,194 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=riscv32 -mattr=-d -mattr=-f -run-pass=legalizer %s -o - \
+# RUN: | FileCheck %s
+
+---
+name:            fptosi_s1_s32
+body:             |
+  bb.1:
+    liveins: $f10_f
+
+    ; CHECK-LABEL: name: fptosi_s1_s32
+    ; CHECK: liveins: $f10_f
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $f10_f
+    ; CHECK-NEXT: ADJCALLSTACKDOWN 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: $x10 = COPY [[COPY]](s32)
+    ; CHECK-NEXT: PseudoCALL target-flags(riscv-call) &__fixsfsi, csr_ilp32_lp64, implicit-def $x1, implicit $x10, implicit-def $x10
+    ; CHECK-NEXT: ADJCALLSTACKUP 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(s32) = COPY $x10
+    ; CHECK-NEXT: $x10 = COPY [[COPY1]](s32)
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %0:_(s32) = COPY $f10_f
+    %1:_(s1) = G_FPTOSI %0(s32)
+    %2:_(s32) = G_ANYEXT %1(s1)
+    $x10 = COPY %2(s32)
+    PseudoRET implicit $x10
+
+...
+---
+name:            fptoui_s1_s32
+body:             |
+  bb.1:
+    liveins: $f10_f
+
+    ; CHECK-LABEL: name: fptoui_s1_s32
+    ; CHECK: liveins: $f10_f
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $f10_f
+    ; CHECK-NEXT: ADJCALLSTACKDOWN 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: $x10 = COPY [[COPY]](s32)
+    ; CHECK-NEXT: PseudoCALL target-flags(riscv-call) &__fixunssfsi, csr_ilp32_lp64, implicit-def $x1, implicit $x10, implicit-def $x10
+    ; CHECK-NEXT: ADJCALLSTACKUP 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(s32) = COPY $x10
+    ; CHECK-NEXT: $x10 = COPY [[COPY1]](s32)
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %0:_(s32) = COPY $f10_f
+    %1:_(s1) = G_FPTOUI %0(s32)
+    %2:_(s32) = G_ANYEXT %1(s1)
+    $x10 = COPY %2(s32)
+    PseudoRET implicit $x10
+
+...
+---
+name:            fptosi_s8_s32
+body:             |
+  bb.1:
+    liveins: $f10_f
+
+    ; CHECK-LABEL: name: fptosi_s8_s32
+    ; CHECK: liveins: $f10_f
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $f10_f
+    ; CHECK-NEXT: ADJCALLSTACKDOWN 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: $x10 = COPY [[COPY]](s32)
+    ; CHECK-NEXT: PseudoCALL target-flags(riscv-call) &__fixsfsi, csr_ilp32_lp64, implicit-def $x1, implicit $x10, implicit-def $x10
+    ; CHECK-NEXT: ADJCALLSTACKUP 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(s32) = COPY $x10
+    ; CHECK-NEXT: $x10 = COPY [[COPY1]](s32)
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %0:_(s32) = COPY $f10_f
+    %1:_(s8) = G_FPTOSI %0(s32)
+    %2:_(s32) = G_ANYEXT %1(s8)
+    $x10 = COPY %2(s32)
+    PseudoRET implicit $x10
+
+...
+---
+name:            fptoui_s8_s32
+body:             |
+  bb.1:
+    liveins: $f10_f
+
+    ; CHECK-LABEL: name: fptoui_s8_s32
+    ; CHECK: liveins: $f10_f
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $f10_f
+    ; CHECK-NEXT: ADJCALLSTACKDOWN 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: $x10 = COPY [[COPY]](s32)
+    ; CHECK-NEXT: PseudoCALL target-flags(riscv-call) &__fixunssfsi, csr_ilp32_lp64, implicit-def $x1, implicit $x10, implicit-def $x10
+    ; CHECK-NEXT: ADJCALLSTACKUP 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(s32) = COPY $x10
+    ; CHECK-NEXT: $x10 = COPY [[COPY1]](s32)
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %0:_(s32) = COPY $f10_f
+    %1:_(s8) = G_FPTOUI %0(s32)
+    %2:_(s32) = G_ANYEXT %1(s8)
+    $x10 = COPY %2(s32)
+    PseudoRET implicit $x10
+
+...
+---
+name:            fptosi_s16_s32
+body:             |
+  bb.1:
+    liveins: $f10_f
+
+    ; CHECK-LABEL: name: fptosi_s16_s32
+    ; CHECK: liveins: $f10_f
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $f10_f
+    ; CHECK-NEXT: ADJCALLSTACKDOWN 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: $x10 = COPY [[COPY]](s32)
+    ; CHECK-NEXT: PseudoCALL target-flags(riscv-call) &__fixsfsi, csr_ilp32_lp64, implicit-def $x1, implicit $x10, implicit-def $x10
+    ; CHECK-NEXT: ADJCALLSTACKUP 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(s32) = COPY $x10
+    ; CHECK-NEXT: $x10 = COPY [[COPY1]](s32)
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %0:_(s32) = COPY $f10_f
+    %1:_(s16) = G_FPTOSI %0(s32)
+    %2:_(s32) = G_ANYEXT %1(s16)
+    $x10 = COPY %2(s32)
+    PseudoRET implicit $x10
+
+...
+---
+name:            fptoui_s16_s32
+body:             |
+  bb.1:
+    liveins: $f10_f
+
+    ; CHECK-LABEL: name: fptoui_s16_s32
+    ; CHECK: liveins: $f10_f
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $f10_f
+    ; CHECK-NEXT: ADJCALLSTACKDOWN 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: $x10 = COPY [[COPY]](s32)
+    ; CHECK-NEXT: PseudoCALL target-flags(riscv-call) &__fixunssfsi, csr_ilp32_lp64, implicit-def $x1, implicit $x10, implicit-def $x10
+    ; CHECK-NEXT: ADJCALLSTACKUP 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(s32) = COPY $x10
+    ; CHECK-NEXT: $x10 = COPY [[COPY1]](s32)
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %0:_(s32) = COPY $f10_f
+    %1:_(s16) = G_FPTOUI %0(s32)
+    %2:_(s32) = G_ANYEXT %1(s16)
+    $x10 = COPY %2(s32)
+    PseudoRET implicit $x10
+
+...
+---
+name:            fptosi_s32_s32
+body:             |
+  bb.1:
+    liveins: $f10_f
+
+    ; CHECK-LABEL: name: fptosi_s32_s32
+    ; CHECK: liveins: $f10_f
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $f10_f
+    ; CHECK-NEXT: ADJCALLSTACKDOWN 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: $x10 = COPY [[COPY]](s32)
+    ; CHECK-NEXT: PseudoCALL target-flags(riscv-call) &__fixsfsi, csr_ilp32_lp64, implicit-def $x1, implicit $x10, implicit-def $x10
+    ; CHECK-NEXT: ADJCALLSTACKUP 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(s32) = COPY $x10
+    ; CHECK-NEXT: $x10 = COPY [[COPY1]](s32)
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %0:_(s32) = COPY $f10_f
+    %1:_(s32) = G_FPTOSI %0(s32)
+    $x10 = COPY %1(s32)
+    PseudoRET implicit $x10
+
+...
+---
+name:            fptoui_s32_s32
+body:             |
+  bb.1:
+    liveins: $f10_f
+
+    ; CHECK-LABEL: name: fptoui_s32_s32
+    ; CHECK: liveins: $f10_f
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $f10_f
+    ; CHECK-NEXT: ADJCALLSTACKDOWN 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: $x10 = COPY [[COPY]](s32)
+    ; CHECK-NEXT: PseudoCALL target-flags(riscv-call) &__fixunssfsi, csr_ilp32_lp64, implicit-def $x1, implicit $x10, implicit-def $x10
+    ; CHECK-NEXT: ADJCALLSTACKUP 0, 0, implicit-def $x2, implicit $x2
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(s32) = COPY $x10
+    ; CHECK-NEXT: $x10 = COPY [[COPY1]](s32)
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %0:_(s32) = COPY $f10_f
+    %1:_(s32) = G_FPTOUI %0(s32)
+    $x10 = COPY %1(s32)
+    PseudoRET implicit $x10
+
+...



More information about the llvm-commits mailing list