[llvm] [RISCV] Mark FLH as canFoldAsLoad. (PR #165974)

[Craig Topper via llvm-commits]

https://github.com/topperc created https://github.com/llvm/llvm-project/pull/165974

None

>From b51218875dbb7fb4a5a9b999b2d5624a0abcc394 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Fri, 31 Oct 2025 16:12:54 -0700
Subject: [PATCH 1/2] [RISCV] Add FP stackmap test.

---
 llvm/test/CodeGen/RISCV/rv64-stackmap-fp.ll | 41 +++++++++++++++++++++
 1 file changed, 41 insertions(+)
 create mode 100644 llvm/test/CodeGen/RISCV/rv64-stackmap-fp.ll

diff --git a/llvm/test/CodeGen/RISCV/rv64-stackmap-fp.ll b/llvm/test/CodeGen/RISCV/rv64-stackmap-fp.ll
new file mode 100644
index 0000000000000..c10ecb208784c
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/rv64-stackmap-fp.ll
@@ -0,0 +1,41 @@
+; RUN: llc -mtriple=riscv64 -mattr=+d,+zfh < %s | FileCheck %s
+
+; CHECK-LABEL:  .section	.llvm_stackmaps
+; CHECK-NEXT:  __LLVM_StackMaps:
+; Header
+; CHECK-NEXT:   .byte   3
+; CHECK-NEXT:   .byte   0
+; CHECK-NEXT:   .half   0
+; Num Functions
+; CHECK-NEXT:   .word   1
+; Num LargeConstants
+; CHECK-NEXT:   .word   0
+; Num Callsites
+; CHECK-NEXT:   .word   1
+
+; Functions and stack size
+; CHECK-NEXT:   .quad   liveArgs
+; CHECK-NEXT:   .quad   16
+; CHECK-NEXT:   .quad   1
+
+; Spilled stack map values.
+;
+; Verify 3 stack map entries.
+;
+; CHECK-LABEL:  .word   .L{{.*}}-liveArgs
+; CHECK-NEXT:   .half   0
+; CHECK-NEXT:   .half   25
+;
+; Check that at least one is a spilled entry from SP.
+; Location: Indirect SP + ...
+; CHECK:        .byte   3
+; CHECK-NEXT:   .byte   0
+; CHECK-NEXT:   .half   8
+; CHECK-NEXT:   .half   2
+; CHECK-NEXT:   .half   0
+; CHECK-NEXT:   .word
+define void @liveArgs(double %arg0, double %arg1, double %arg2, double %arg3, double %arg4, double %arg5, double %arg6, double %arg7, double %arg8, double %arg9, double %arg10, double %arg11, double %arg12, double %arg13, double %arg14, double %arg15, double %arg16, double %arg17, double %arg18, double %arg19, double %arg20, double %arg21, double %arg22, double %arg23, half %arg24, half %arg25, half %arg26, half %arg27, half %arg28, bfloat %arg29) {
+entry:
+  call void (i64, i32, ptr, i32, ...) @llvm.experimental.patchpoint.void(i64 11, i32 28, ptr null, i32 5, double %arg0, double %arg1, double %arg2, double %arg3, double %arg4, double %arg5, double %arg6, double %arg7, double %arg8, double %arg9, double %arg10, double %arg11, double %arg12, double %arg13, double %arg14, double %arg15, double %arg16, double %arg17, double %arg18, double %arg19, double %arg20, double %arg21, double %arg22, double %arg23, half %arg24, half %arg25, half %arg26, half %arg27, half %arg28, bfloat %arg29)
+  ret void
+}

>From 9edb886a597d374b215664b1b8c2ef550da36696 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper at sifive.com>
Date: Fri, 31 Oct 2025 23:27:15 -0700
Subject: [PATCH 2/2] [RISCV] Mark FLH as canFoldAsLoad.

---
 llvm/lib/Target/RISCV/RISCVInstrInfoZfh.td  | 1 +
 llvm/test/CodeGen/RISCV/rv64-stackmap-fp.ll | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoZfh.td b/llvm/lib/Target/RISCV/RISCVInstrInfoZfh.td
index c31713e967b18..1c6a5afcda49b 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfoZfh.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfoZfh.td
@@ -90,6 +90,7 @@ defvar ZfhminDExts = [ZfhminDExt, ZhinxminZdinxExt, ZhinxminZdinx32Ext];
 //===----------------------------------------------------------------------===//
 
 let Predicates = [HasHalfFPLoadStoreMove] in {
+let canFoldAsLoad = 1 in
 def FLH : FPLoad_r<0b001, "flh", FPR16, WriteFLD16>;
 
 // Operands for stores are in the order srcreg, base, offset rather than
diff --git a/llvm/test/CodeGen/RISCV/rv64-stackmap-fp.ll b/llvm/test/CodeGen/RISCV/rv64-stackmap-fp.ll
index c10ecb208784c..bf0a2e5e35a01 100644
--- a/llvm/test/CodeGen/RISCV/rv64-stackmap-fp.ll
+++ b/llvm/test/CodeGen/RISCV/rv64-stackmap-fp.ll
@@ -15,7 +15,7 @@
 
 ; Functions and stack size
 ; CHECK-NEXT:   .quad   liveArgs
-; CHECK-NEXT:   .quad   16
+; CHECK-NEXT:   .quad   0
 ; CHECK-NEXT:   .quad   1
 
 ; Spilled stack map values.