[llvm] [RISCV] Support PreserveMost calling convention (PR #148214)

Brandon Wu via llvm-commits llvm-commits at lists.llvm.org
Fri Jul 11 13:17:19 PDT 2025


================
@@ -0,0 +1,165 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=riscv32 < %s | FileCheck %s -check-prefix=RV32
+; RUN: llc -mtriple=riscv64 < %s | FileCheck %s -check-prefix=RV64
+
+; Check the PreserveMost calling convention works.
+
+declare void @standard_cc_func()
+declare preserve_mostcc void @preserve_mostcc_func()
+
+define preserve_mostcc void @preserve_mostcc1() nounwind {
+; RV32-LABEL: preserve_mostcc1:
+; RV32:       # %bb.0: # %entry
+; RV32-NEXT:    addi sp, sp, -64
+; RV32-NEXT:    sw t0, 60(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t1, 56(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t2, 52(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a0, 48(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a1, 44(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a2, 40(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a3, 36(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a4, 32(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a5, 28(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a6, 24(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw a7, 20(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t3, 16(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t4, 12(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t5, 8(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw t6, 4(sp) # 4-byte Folded Spill
+; RV32-NEXT:    call standard_cc_func
+; RV32-NEXT:    lw t0, 60(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t1, 56(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t2, 52(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a0, 48(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a1, 44(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a2, 40(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a3, 36(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a4, 32(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a5, 28(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a6, 24(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw a7, 20(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t3, 16(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t4, 12(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t5, 8(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw t6, 4(sp) # 4-byte Folded Reload
+; RV32-NEXT:    addi sp, sp, 64
+; RV32-NEXT:    ret
+;
+; RV64-LABEL: preserve_mostcc1:
+; RV64:       # %bb.0: # %entry
+; RV64-NEXT:    addi sp, sp, -128
+; RV64-NEXT:    sd t0, 120(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t1, 112(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t2, 104(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a0, 96(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a1, 88(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a2, 80(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a3, 72(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a4, 64(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a5, 56(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a6, 48(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd a7, 40(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t3, 32(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t4, 24(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t5, 16(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd t6, 8(sp) # 8-byte Folded Spill
+; RV64-NEXT:    call standard_cc_func
+; RV64-NEXT:    ld t0, 120(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t1, 112(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t2, 104(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a0, 96(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a1, 88(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a2, 80(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a3, 72(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a4, 64(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a5, 56(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a6, 48(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld a7, 40(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t3, 32(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t4, 24(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t5, 16(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld t6, 8(sp) # 8-byte Folded Reload
+; RV64-NEXT:    addi sp, sp, 128
+; RV64-NEXT:    ret
+entry:
+  call void @standard_cc_func()
+  ret void
+}
+
+define preserve_mostcc void @preserve_mostcc2() nounwind {
----------------
4vtomat wrote:

Curious about why this function emits same spills as `preserve_mostcc1`?

https://github.com/llvm/llvm-project/pull/148214


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