[llvm-branch-commits] [llvm] 6b52570 - [RISCV] Fix vmerge.vvm/vmv.v.v getting folded into ops with mismatching EEW (#101152)

[Tobias Hieta via llvm-branch-commits]

Author: Luke Lau
Date: 2024-08-02T12:10:42+02:00
New Revision: 6b52570dcd5d34a9b44ccd0bb2b2d4ffd661d9d7

URL: https://github.com/llvm/llvm-project/commit/6b52570dcd5d34a9b44ccd0bb2b2d4ffd661d9d7
DIFF: https://github.com/llvm/llvm-project/commit/6b52570dcd5d34a9b44ccd0bb2b2d4ffd661d9d7.diff

LOG: [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

Added: 
    

Modified: 
    llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
    llvm/test/CodeGen/RISCV/rvv/combine-vmv.ll
    llvm/test/CodeGen/RISCV/rvv/rvv-peephole-vmerge-vops.ll

Removed: 
    


################################################################################
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 
diff erent 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
+}