From 75d820dcdd868b8ab6c12ff62f90216ad377ce20 Mon Sep 17 00:00:00 2001 From: Sjoerd Meijer Date: Thu, 11 Jan 2024 09:46:47 +0000 Subject: [PATCH] [AArch64] MI Scheduler: create more LDP/STP pairs (#77565) Target hook `canPairLdStOpc` is missing quite a few opcodes for which LDPs/STPs can created. I was hoping that it would not be necessary to add these missing opcodes here and that the attached motivating test case would be handled by the LoadStoreOptimiser (especially after #71908), but it's not. The problem is that after register allocation some things are a lot harder to do. Consider this for the motivating example ``` [1] renamable $q1 = LDURQi renamable $x9, -16 :: (load (s128) from %ir.r51, align 8, !tbaa !0) [2] renamable $q2 = LDURQi renamable $x0, -16 :: (load (s128) from %ir.r53, align 8, !tbaa !4) [3] renamable $q1 = nnan ninf nsz arcp contract afn reassoc nofpexcept FMLSv2f64 killed renamable $q1(tied-def 0), killed renamable $q2, renamable $q0, implicit $fpcr [4] STURQi killed renamable $q1, renamable $x9, -16 :: (store (s128) into %ir.r51, align 1, !tbaa !0) [5] renamable $q1 = LDRQui renamable $x9, 0 :: (load (s128) from %ir.r.G0001_609.0, align 8, !tbaa !0) ``` We can't combine the the load in line [5] into the load on [1]: regisister q1 is used in between. And we can can't combine [1] into [5]: it is aliasing with the STR on line [4]. So, adding some missing opcodes here seems the best/easiest approach. I will follow up to add some more missing cases here. --- llvm/lib/Target/AArch64/AArch64InstrInfo.cpp | 3 ++ .../test/CodeGen/AArch64/arm64-ldp-cluster.ll | 41 +++++++++++++++++++ .../CodeGen/AArch64/machine-combiner-copy.ll | 8 ++-- 3 files changed, 48 insertions(+), 4 deletions(-) diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp index 1cfbf4737a6f..42b7a6418032 100644 --- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp +++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp @@ -4214,6 +4214,9 @@ static bool canPairLdStOpc(unsigned FirstOpc, unsigned SecondOpc) { switch (FirstOpc) { default: return false; + case AArch64::LDRQui: + case AArch64::LDURQi: + return SecondOpc == AArch64::LDRQui || SecondOpc == AArch64::LDURQi; case AArch64::LDRWui: case AArch64::LDURWi: return SecondOpc == AArch64::LDRSWui || SecondOpc == AArch64::LDURSWi; diff --git a/llvm/test/CodeGen/AArch64/arm64-ldp-cluster.ll b/llvm/test/CodeGen/AArch64/arm64-ldp-cluster.ll index 4fa34e846b20..83f86d1c3a7c 100644 --- a/llvm/test/CodeGen/AArch64/arm64-ldp-cluster.ll +++ b/llvm/test/CodeGen/AArch64/arm64-ldp-cluster.ll @@ -113,3 +113,44 @@ define <2 x i64> @ldq_cluster(ptr %p) { %res = mul nsw <2 x i64> %tmp2, %tmp3 ret <2 x i64> %res } + +; Test LDURQi / LDRQui clustering +; +; CHECK: ********** MI Scheduling ********** +; CHECK: LDURQi_LDRQui:%bb.1 vector_body +; +; CHECK: Cluster ld/st SU(0) - SU(4) +; CHECK: Cluster ld/st SU(1) - SU(5) +; +; CHECK: SU(0): %{{[0-9]+}}:fpr128 = LDURQi +; CHECK: SU(1): %{{[0-9]+}}:fpr128 = LDURQi +; CHECK: SU(4): %{{[0-9]+}}:fpr128 = LDRQui +; CHECK: SU(5): %{{[0-9]+}}:fpr128 = LDRQui +; +define void @LDURQi_LDRQui(ptr nocapture readonly %arg) { +entry: + br label %vector_body +vector_body: + %phi1 = phi ptr [ null, %entry ], [ %r63, %vector_body ] + %phi2 = phi ptr [ %arg, %entry ], [ %r62, %vector_body ] + %phi3 = phi i32 [ 0, %entry ], [ %r61, %vector_body ] + %r51 = getelementptr i8, ptr %phi1, i64 -16 + %r52 = load <2 x double>, ptr %r51, align 8 + %r53 = getelementptr i8, ptr %phi2, i64 -16 + %r54 = load <2 x double>, ptr %r53, align 8 + %r55 = fmul fast <2 x double> %r54, + %r56 = fsub fast <2 x double> %r52, %r55 + store <2 x double> %r56, ptr %r51, align 1 + %r57 = load <2 x double>, ptr %phi1, align 8 + %r58 = load <2 x double>, ptr %phi2, align 8 + %r59 = fmul fast <2 x double> %r58, + %r60 = fsub fast <2 x double> %r57, %r59 + store <2 x double> %r60, ptr %phi1, align 1 + %r61 = add i32 %phi3, 4 + %r62 = getelementptr i8, ptr %phi2, i64 32 + %r63 = getelementptr i8, ptr %phi1, i64 32 + %r.not = icmp eq i32 %r61, 0 + br i1 %r.not, label %exit, label %vector_body +exit: + ret void +} diff --git a/llvm/test/CodeGen/AArch64/machine-combiner-copy.ll b/llvm/test/CodeGen/AArch64/machine-combiner-copy.ll index 15a484d11b0a..4c8e589391c3 100644 --- a/llvm/test/CodeGen/AArch64/machine-combiner-copy.ll +++ b/llvm/test/CodeGen/AArch64/machine-combiner-copy.ll @@ -20,13 +20,13 @@ define void @fma_dup_f16(ptr noalias nocapture noundef readonly %A, half noundef ; CHECK-NEXT: mov x12, x9 ; CHECK-NEXT: .LBB0_4: // %vector.body ; CHECK-NEXT: // =>This Inner Loop Header: Depth=1 -; CHECK-NEXT: ldp q1, q3, [x11, #-16] +; CHECK-NEXT: ldp q1, q4, [x10, #-16] ; CHECK-NEXT: subs x12, x12, #16 -; CHECK-NEXT: ldp q2, q4, [x10, #-16] +; CHECK-NEXT: ldp q2, q3, [x11, #-16] ; CHECK-NEXT: add x11, x11, #32 -; CHECK-NEXT: fmla v2.8h, v1.8h, v0.h[0] +; CHECK-NEXT: fmla v1.8h, v2.8h, v0.h[0] ; CHECK-NEXT: fmla v4.8h, v3.8h, v0.h[0] -; CHECK-NEXT: stp q2, q4, [x10, #-16] +; CHECK-NEXT: stp q1, q4, [x10, #-16] ; CHECK-NEXT: add x10, x10, #32 ; CHECK-NEXT: b.ne .LBB0_4 ; CHECK-NEXT: // %bb.5: // %middle.block