https://github.com/lukel97 created https://github.com/llvm/llvm-project/pull/101464
This is a backport of #101152 which fixes a miscompile on RISC-V, albeit not a regression. >From 6b7c614ad8a69dfb610ed02da541fb8d3bf009e3 Mon Sep 17 00:00:00 2001 From: Luke Lau <l...@igalia.com> Date: Wed, 31 Jul 2024 00:28:52 +0800 Subject: [PATCH] [RISCV] Fix vmerge.vvm/vmv.v.v getting folded into ops with mismatching EEW (#101152) As noted in https://github.com/llvm/llvm-project/pull/100367/files#r1695448771, we currently fold in vmerge.vvms and vmv.v.vs into their ops even if the EEW is different which leads to an incorrect transform. This checks the op's EEW via its simple value type for now since there doesn't seem to be any existing information about the EEW size of instructions. We'll probably need to encode this at some point if we want to be able to access it at the MachineInstr level in #100367 --- llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp | 4 ++++ llvm/test/CodeGen/RISCV/rvv/combine-vmv.ll | 14 +++++++++++++ .../RISCV/rvv/rvv-peephole-vmerge-vops.ll | 21 +++++++++++++++++++ 3 files changed, 39 insertions(+) diff --git a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp index eef6ae677ac85..db949f3476e2b 100644 --- a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp +++ b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp @@ -3721,6 +3721,10 @@ bool RISCVDAGToDAGISel::performCombineVMergeAndVOps(SDNode *N) { assert(!Mask || cast<RegisterSDNode>(Mask)->getReg() == RISCV::V0); assert(!Glue || Glue.getValueType() == MVT::Glue); + // If the EEW of True is different from vmerge's SEW, then we can't fold. + if (True.getSimpleValueType() != N->getSimpleValueType(0)) + return false; + // We require that either merge and false are the same, or that merge // is undefined. if (Merge != False && !isImplicitDef(Merge)) diff --git a/llvm/test/CodeGen/RISCV/rvv/combine-vmv.ll b/llvm/test/CodeGen/RISCV/rvv/combine-vmv.ll index ec03f773c7108..dfc2b2bdda026 100644 --- a/llvm/test/CodeGen/RISCV/rvv/combine-vmv.ll +++ b/llvm/test/CodeGen/RISCV/rvv/combine-vmv.ll @@ -168,3 +168,17 @@ define <vscale x 2 x i32> @unfoldable_vredsum(<vscale x 2 x i32> %passthru, <vsc %b = call <vscale x 2 x i32> @llvm.riscv.vmv.v.v.nxv2i32(<vscale x 2 x i32> %passthru, <vscale x 2 x i32> %a, iXLen 1) ret <vscale x 2 x i32> %b } + +define <vscale x 2 x i32> @unfoldable_mismatched_sew(<vscale x 2 x i32> %passthru, <vscale x 1 x i64> %x, <vscale x 1 x i64> %y, iXLen %avl) { +; CHECK-LABEL: unfoldable_mismatched_sew: +; CHECK: # %bb.0: +; CHECK-NEXT: vsetvli zero, a0, e64, m1, ta, ma +; CHECK-NEXT: vadd.vv v9, v9, v10 +; CHECK-NEXT: vsetvli zero, a0, e32, m1, tu, ma +; CHECK-NEXT: vmv.v.v v8, v9 +; CHECK-NEXT: ret + %a = call <vscale x 1 x i64> @llvm.riscv.vadd.nxv1i64.nxv1i64(<vscale x 1 x i64> poison, <vscale x 1 x i64> %x, <vscale x 1 x i64> %y, iXLen %avl) + %a.bitcast = bitcast <vscale x 1 x i64> %a to <vscale x 2 x i32> + %b = call <vscale x 2 x i32> @llvm.riscv.vmv.v.v.nxv2i32(<vscale x 2 x i32> %passthru, <vscale x 2 x i32> %a.bitcast, iXLen %avl) + ret <vscale x 2 x i32> %b +} diff --git a/llvm/test/CodeGen/RISCV/rvv/rvv-peephole-vmerge-vops.ll b/llvm/test/CodeGen/RISCV/rvv/rvv-peephole-vmerge-vops.ll index a08bcae074b9b..259515f160048 100644 --- a/llvm/test/CodeGen/RISCV/rvv/rvv-peephole-vmerge-vops.ll +++ b/llvm/test/CodeGen/RISCV/rvv/rvv-peephole-vmerge-vops.ll @@ -1196,3 +1196,24 @@ define <vscale x 2 x i32> @true_mask_vmerge_implicit_passthru(<vscale x 2 x i32> ) ret <vscale x 2 x i32> %b } + + +define <vscale x 2 x i32> @unfoldable_mismatched_sew(<vscale x 2 x i32> %passthru, <vscale x 1 x i64> %x, <vscale x 1 x i64> %y, <vscale x 2 x i1> %mask, i64 %avl) { +; CHECK-LABEL: unfoldable_mismatched_sew: +; CHECK: # %bb.0: +; CHECK-NEXT: vsetvli zero, a0, e64, m1, ta, ma +; CHECK-NEXT: vadd.vv v9, v9, v10 +; CHECK-NEXT: vsetvli zero, a0, e32, m1, tu, ma +; CHECK-NEXT: vmv.v.v v8, v9 +; CHECK-NEXT: ret + %a = call <vscale x 1 x i64> @llvm.riscv.vadd.nxv1i64.nxv1i64(<vscale x 1 x i64> poison, <vscale x 1 x i64> %x, <vscale x 1 x i64> %y, i64 %avl) + %a.bitcast = bitcast <vscale x 1 x i64> %a to <vscale x 2 x i32> + %b = call <vscale x 2 x i32> @llvm.riscv.vmerge.nxv2i32.nxv2i32( + <vscale x 2 x i32> %passthru, + <vscale x 2 x i32> %passthru, + <vscale x 2 x i32> %a.bitcast, + <vscale x 2 x i1> splat (i1 true), + i64 %avl + ) + ret <vscale x 2 x i32> %b +} _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
