[llvm] [RISCV][GISel] Legalize the G_FCANONICALIZE instruction (PR #166162)

[Chuan-Yue Yuan via llvm-commits]

https://github.com/circYuan created https://github.com/llvm/llvm-project/pull/166162

None

>From 42e99217680c7b3191d0139e636daad2cae77762 Mon Sep 17 00:00:00 2001
From: circYuan <quanyueyuan at gmail.com>
Date: Sat, 1 Nov 2025 14:46:56 +0800
Subject: [PATCH] [RISCV][GISel] Legalize the G_FCANONICALIZE instruction

---
 .../Target/RISCV/GISel/RISCVLegalizerInfo.cpp |  5 ++
 .../RISCV/GlobalISel/fp-fcanonicalize.ll      | 66 +++++++++++++++++++
 .../GlobalISel/legalizer-info-validation.mir  |  4 +-
 3 files changed, 73 insertions(+), 2 deletions(-)
 create mode 100644 llvm/test/CodeGen/RISCV/GlobalISel/fp-fcanonicalize.ll

diff --git a/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp b/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp
index b1794b78a3e2a..d68dc3c8d991f 100644
--- a/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp
+++ b/llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp
@@ -636,6 +636,11 @@ RISCVLegalizerInfo::RISCVLegalizerInfo(const RISCVSubtarget &ST)
       .libcallFor({{s32, s32}, {s64, s32}})
       .libcallFor(ST.is64Bit(), {s128, s32});
 
+  getActionDefinitionsBuilder(G_FCANONICALIZE)
+      .legalFor(ST.hasStdExtF(), {s32})
+      .legalFor(ST.hasStdExtD(), {s64})
+      .legalFor(ST.hasStdExtZfh(), {s16});
+
   getActionDefinitionsBuilder(G_VASTART).customFor({p0});
 
   // va_list must be a pointer, but most sized types are pretty easy to handle
diff --git a/llvm/test/CodeGen/RISCV/GlobalISel/fp-fcanonicalize.ll b/llvm/test/CodeGen/RISCV/GlobalISel/fp-fcanonicalize.ll
new file mode 100644
index 0000000000000..d983082083ecb
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/GlobalISel/fp-fcanonicalize.ll
@@ -0,0 +1,66 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; FIXME: @llvm.canonicalize doesn't support soft-float abi yet.
+; RUN: llc -mtriple=riscv64 -mattr=+d,+zfh -global-isel < %s | FileCheck %s --check-prefixes=CHECK,CHECK-FP16-RV64
+; RUN: llc -mtriple=riscv32 -mattr=+d,+zfh -global-isel < %s | FileCheck %s --check-prefixes=CHECK,CHECK-FP16-RV32
+
+declare half @llvm.fcanonicalize.f16(half)
+declare float @llvm.fcanonicalize.f32(float)
+declare double @llvm.fcanonicalize.f64(double)
+
+define half @fcanonicalize_f16(half %x) {
+; CHECK-LABEL: fcanonicalize_f16:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    fmin.h fa0, fa0, fa0
+; CHECK-NEXT:    ret
+  %z = call half @llvm.canonicalize.f16(half %x)
+  ret half %z
+}
+
+define half @fcanonicalize_f16_nnan(half %x) {
+; CHECK-LABEL: fcanonicalize_f16_nnan:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    fmin.h fa0, fa0, fa0
+; CHECK-NEXT:    ret
+  %z = call nnan half @llvm.canonicalize.f16(half %x)
+  ret half %z
+}
+
+define float @fcanonicalize_f32(float %x) {
+; CHECK-LABEL: fcanonicalize_f32:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    fmin.s fa0, fa0, fa0
+; CHECK-NEXT:    ret
+  %z = call float @llvm.canonicalize.f32(float %x)
+  ret float %z
+}
+
+define float @fcanonicalize_f32_nnan(float %x) {
+; CHECK-LABEL: fcanonicalize_f32_nnan:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    fmin.s fa0, fa0, fa0
+; CHECK-NEXT:    ret
+  %z = call nnan float @llvm.canonicalize.f32(float %x)
+  ret float %z
+}
+
+define double @fcanonicalize_f64(double %x) {
+; CHECK-LABEL: fcanonicalize_f64:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    fmin.d fa0, fa0, fa0
+; CHECK-NEXT:    ret
+  %z = call double @llvm.canonicalize.f64(double %x)
+  ret double %z
+}
+
+define double @fcanonicalize_f64_nnan(double %x) {
+; CHECK-LABEL: fcanonicalize_f64_nnan:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    fmin.d fa0, fa0, fa0
+; CHECK-NEXT:    ret
+  %z = call nnan double @llvm.canonicalize.f64(double %x)
+  ret double %z
+}
+
+;; NOTE: These prefixes are unused and the list is autogenerated. Do not add tests below this line:
+; CHECK-FP16-RV32: {{.*}}
+; CHECK-FP16-RV64: {{.*}}
diff --git a/llvm/test/CodeGen/RISCV/GlobalISel/legalizer-info-validation.mir b/llvm/test/CodeGen/RISCV/GlobalISel/legalizer-info-validation.mir
index da7546e12e58b..5f9b647112a50 100644
--- a/llvm/test/CodeGen/RISCV/GlobalISel/legalizer-info-validation.mir
+++ b/llvm/test/CodeGen/RISCV/GlobalISel/legalizer-info-validation.mir
@@ -587,8 +587,8 @@
 # DEBUG-NEXT: .. the first uncovered type index: 2, OK
 # DEBUG-NEXT: .. the first uncovered imm index: 0, OK
 # DEBUG-NEXT: G_FCANONICALIZE (opcode {{[0-9]+}}): 1 type index, 0 imm indices
-# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
-# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
+# DEBUG-NEXT: .. the first uncovered type index: 1, OK
+# DEBUG-NEXT: .. the first uncovered imm index: 0, OK
 # DEBUG-NEXT: G_FMINNUM (opcode {{[0-9]+}}): 1 type index
 # DEBUG-NEXT: .. opcode {{[0-9]+}} is aliased to {{[0-9]+}}
 # DEBUG-NEXT: .. the first uncovered type index: 1, OK