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[AArch64] Avoid single-element vector fp converts in streaming[-compatible] functions #112213

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Oct 16, 2024
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[AArch64] Avoid single-element vector fp converts in streaming[-compatible] functions #112213

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713d4c6
[AArch64] Avoid single-element vector fp converts in streaming[-compa…
MacDue Oct 14, 2024
decbae4
Fix typo
MacDue Oct 14, 2024
122d5ea
Fixups
MacDue Oct 14, 2024
80227ae
Add TODOs & test updates
MacDue Oct 15, 2024
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15 changes: 9 additions & 6 deletions llvm/lib/Target/AArch64/AArch64InstrInfo.td
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Original file line number Diff line number Diff line change
Expand Up @@ -6237,7 +6237,8 @@ def : Pat<(v2f64 (AArch64frsqrts (v2f64 FPR128:$Rn), (v2f64 FPR128:$Rm))),
// Some float -> int -> float conversion patterns for which we want to keep the
// int values in FP registers using the corresponding NEON instructions to
// avoid more costly int <-> fp register transfers.
let Predicates = [HasNEONandIsStreamingSafe] in {
// TODO: Allow these in streaming[-compatible] functions with +sme2p2.
let Predicates = [HasNEON] in {
def : Pat<(f64 (any_sint_to_fp (i64 (any_fp_to_sint f64:$Rn)))),
(SCVTFv1i64 (i64 (FCVTZSv1i64 f64:$Rn)))>;
def : Pat<(f32 (any_sint_to_fp (i32 (any_fp_to_sint f32:$Rn)))),
Expand All @@ -6247,7 +6248,8 @@ def : Pat<(f64 (any_uint_to_fp (i64 (any_fp_to_uint f64:$Rn)))),
def : Pat<(f32 (any_uint_to_fp (i32 (any_fp_to_uint f32:$Rn)))),
(UCVTFv1i32 (i32 (FCVTZUv1i32 f32:$Rn)))>;

let Predicates = [HasNEONandIsStreamingSafe, HasFullFP16] in {
// TODO: Allow these in streaming[-compatible] functions with +sme2p2.
let Predicates = [HasNEON, HasFullFP16] in {
def : Pat<(f16 (any_sint_to_fp (i32 (any_fp_to_sint f16:$Rn)))),
(SCVTFv1i16 (f16 (FCVTZSv1f16 f16:$Rn)))>;
def : Pat<(f16 (any_uint_to_fp (i32 (any_fp_to_uint f16:$Rn)))),
Expand All @@ -6270,9 +6272,10 @@ def : Pat<(f64 (uint_to_fp (i64 (vector_extract (v2i64 FPR128:$Rn), (i64 0))))),

// fp16: integer extraction from vector must be at least 32-bits to be legal.
// Actual extraction result is then an in-reg sign-extension of lower 16-bits.
let Predicates = [HasNEONandIsStreamingSafe, HasFullFP16] in {
def : Pat<(f16 (sint_to_fp (i32 (sext_inreg (i32 (vector_extract
(v8i16 FPR128:$Rn), (i64 0))), i16)))),
// TODO: Allow these in streaming[-compatible] functions with +sme2p2.
let Predicates = [HasNEON, HasFullFP16] in {
def : Pat<(f16 (sint_to_fp (i32 (sext_inreg (i32 (vector_extract
(v8i16 FPR128:$Rn), (i64 0))), i16)))),
(SCVTFv1i16 (f16 (EXTRACT_SUBREG (v8i16 FPR128:$Rn), hsub)))>;

// unsigned 32-bit extracted element is truncated to 16-bits using AND
Expand Down Expand Up @@ -6367,7 +6370,7 @@ def : Pat <(f64 (uint_to_fp (i32
(LDURSi GPR64sp:$Rn, simm9:$offset), ssub))>;
// 64-bits -> double are handled in target specific dag combine:
// performIntToFpCombine.
} // let Predicates = [HasNEONandIsStreamingSafe]
} // let Predicates = [HasNEON]

//===----------------------------------------------------------------------===//
// Advanced SIMD three different-sized vector instructions.
Expand Down
121 changes: 121 additions & 0 deletions llvm/test/CodeGen/AArch64/sve-streaming-mode-cvt-fp-int-fp.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,121 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -force-streaming-compatible < %s | FileCheck %s
; RUN: llc < %s | FileCheck %s --check-prefix=NON-STREAMING

target triple = "aarch64-unknown-linux-gnu"

define double @t1(double %x) {
; CHECK-LABEL: t1:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: fcvtzs x8, d0
; CHECK-NEXT: scvtf d0, x8
Comment on lines +10 to +11
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This operation may be expensive when executed in streaming mode, because the operations move results between register files (FPR <-> GPR). Could you emulate this operation with SVE instructions instead?
I'm happy for this to be done in a separate patch so that this bugfix can already land.

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@MacDue MacDue Oct 14, 2024 •
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I'll look into that in a follow up patch 👍 I need to check how to do something ~equivalent for SVE since for Neon this is done via a load of .td patterns (matching both the to/from int parts).

; CHECK-NEXT: ret
;
; NON-STREAMING-LABEL: t1:
; NON-STREAMING: // %bb.0: // %entry
; NON-STREAMING-NEXT: fcvtzs d0, d0
; NON-STREAMING-NEXT: scvtf d0, d0
; NON-STREAMING-NEXT: ret
entry:
%conv = fptosi double %x to i64
%conv1 = sitofp i64 %conv to double
ret double %conv1
}

define float @t2(float %x) {
; CHECK-LABEL: t2:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: fcvtzs w8, s0
; CHECK-NEXT: scvtf s0, w8
; CHECK-NEXT: ret
;
; NON-STREAMING-LABEL: t2:
; NON-STREAMING: // %bb.0: // %entry
; NON-STREAMING-NEXT: fcvtzs s0, s0
; NON-STREAMING-NEXT: scvtf s0, s0
; NON-STREAMING-NEXT: ret
entry:
%conv = fptosi float %x to i32
%conv1 = sitofp i32 %conv to float
ret float %conv1
}

define half @t3(half %x) {
; CHECK-LABEL: t3:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: fcvt s0, h0
; CHECK-NEXT: fcvtzs w8, s0
; CHECK-NEXT: scvtf s0, w8
; CHECK-NEXT: fcvt h0, s0
; CHECK-NEXT: ret
;
; NON-STREAMING-LABEL: t3:
; NON-STREAMING: // %bb.0: // %entry
; NON-STREAMING-NEXT: fcvt s0, h0
; NON-STREAMING-NEXT: fcvtzs s0, s0
; NON-STREAMING-NEXT: scvtf s0, s0
; NON-STREAMING-NEXT: fcvt h0, s0
; NON-STREAMING-NEXT: ret
entry:
%conv = fptosi half %x to i32
%conv1 = sitofp i32 %conv to half
ret half %conv1
}

define double @t4(double %x) {
; CHECK-LABEL: t4:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: fcvtzu x8, d0
; CHECK-NEXT: ucvtf d0, x8
; CHECK-NEXT: ret
;
; NON-STREAMING-LABEL: t4:
; NON-STREAMING: // %bb.0: // %entry
; NON-STREAMING-NEXT: fcvtzu d0, d0
; NON-STREAMING-NEXT: ucvtf d0, d0
; NON-STREAMING-NEXT: ret
entry:
%conv = fptoui double %x to i64
%conv1 = uitofp i64 %conv to double
ret double %conv1
}

define float @t5(float %x) {
; CHECK-LABEL: t5:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: fcvtzu w8, s0
; CHECK-NEXT: ucvtf s0, w8
; CHECK-NEXT: ret
;
; NON-STREAMING-LABEL: t5:
; NON-STREAMING: // %bb.0: // %entry
; NON-STREAMING-NEXT: fcvtzu s0, s0
; NON-STREAMING-NEXT: ucvtf s0, s0
; NON-STREAMING-NEXT: ret
entry:
%conv = fptoui float %x to i32
%conv1 = uitofp i32 %conv to float
ret float %conv1
}

define half @t6(half %x) {
; CHECK-LABEL: t6:
; CHECK: // %bb.0: // %entry
; CHECK-NEXT: fcvt s0, h0
; CHECK-NEXT: fcvtzu w8, s0
; CHECK-NEXT: ucvtf s0, w8
; CHECK-NEXT: fcvt h0, s0
; CHECK-NEXT: ret
;
; NON-STREAMING-LABEL: t6:
; NON-STREAMING: // %bb.0: // %entry
; NON-STREAMING-NEXT: fcvt s0, h0
; NON-STREAMING-NEXT: fcvtzu s0, s0
; NON-STREAMING-NEXT: ucvtf s0, s0
; NON-STREAMING-NEXT: fcvt h0, s0
; NON-STREAMING-NEXT: ret
entry:
%conv = fptoui half %x to i32
%conv1 = uitofp i32 %conv to half
ret half %conv1
}
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