[PATCH] D140106: [AggressiveInstCombine] Fix invalid TypeSize conversion when combining loads.

[Paul Walker via Phabricator via llvm-commits]

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Much of foldLoadsRecursive relies on knowing the size of loaded
data, which is not possible for scalable vector types.  However,
the logic of combining two small loads into one bigger load does
not apply for vector types so rather than converting the algorithm
to use TypeSize I've simply added an early exit for vectors.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D140106

Files:
  llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
  llvm/test/Transforms/AggressiveInstCombine/vector-or-load.ll


Index: llvm/test/Transforms/AggressiveInstCombine/vector-or-load.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/AggressiveInstCombine/vector-or-load.ll
@@ -0,0 +1,50 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=aggressive-instcombine -S | FileCheck %s
+
+; Use the same idoim as X86/or-load.ll @loadCombine_2consecutive to represent a
+; sequence of operations that can be replaced by a single double-width load when
+; using scalar types but whose logic does not apply to fixed length vectors.
+define <8 x i16> @or-load-fixed-length-vector(ptr %p1) {
+; CHECK-LABEL: @or-load-fixed-length-vector(
+; CHECK-NEXT:    [[P2:%.*]] = getelementptr i8, ptr [[P1:%.*]], i32 1
+; CHECK-NEXT:    [[L1:%.*]] = load <8 x i8>, ptr [[P1]], align 1
+; CHECK-NEXT:    [[L2:%.*]] = load <8 x i8>, ptr [[P2]], align 1
+; CHECK-NEXT:    [[E1:%.*]] = zext <8 x i8> [[L1]] to <8 x i16>
+; CHECK-NEXT:    [[E2:%.*]] = zext <8 x i8> [[L2]] to <8 x i16>
+; CHECK-NEXT:    [[S2:%.*]] = shl <8 x i16> [[E2]], <i16 8, i16 8, i16 8, i16 8, i16 8, i16 8, i16 8, i16 8>
+; CHECK-NEXT:    [[OR:%.*]] = or <8 x i16> [[E1]], [[S2]]
+; CHECK-NEXT:    ret <8 x i16> [[OR]]
+;
+  %p2 = getelementptr i8, ptr %p1, i32 1
+  %l1 = load <8 x i8>, ptr %p1, align 1
+  %l2 = load <8 x i8>, ptr %p2, align 1
+  %e1 = zext <8 x i8> %l1 to <8 x i16>
+  %e2 = zext <8 x i8> %l2 to <8 x i16>
+  %s2 = shl <8 x i16> %e2, <i16 8, i16 8, i16 8, i16 8, i16 8, i16 8, i16 8, i16 8>
+  %or = or <8 x i16> %e1, %s2
+  ret <8 x i16> %or
+}
+
+; Use the same idoim as X86/or-load.ll @loadCombine_2consecutive to represent a
+; sequence of operations that can be replaced by a single double-width load when
+; using scalar types but whose logic does not apply to scalable length vectors.
+define <vscale x 8 x i16> @or-load-scalable-vector(ptr %p1) {
+; CHECK-LABEL: @or-load-scalable-vector(
+; CHECK-NEXT:    [[P2:%.*]] = getelementptr i8, ptr [[P1:%.*]], i32 1
+; CHECK-NEXT:    [[L1:%.*]] = load <vscale x 8 x i8>, ptr [[P1]], align 1
+; CHECK-NEXT:    [[L2:%.*]] = load <vscale x 8 x i8>, ptr [[P2]], align 1
+; CHECK-NEXT:    [[E1:%.*]] = zext <vscale x 8 x i8> [[L1]] to <vscale x 8 x i16>
+; CHECK-NEXT:    [[E2:%.*]] = zext <vscale x 8 x i8> [[L2]] to <vscale x 8 x i16>
+; CHECK-NEXT:    [[S2:%.*]] = shl <vscale x 8 x i16> [[E2]], shufflevector (<vscale x 8 x i16> insertelement (<vscale x 8 x i16> poison, i16 8, i32 0), <vscale x 8 x i16> poison, <vscale x 8 x i32> zeroinitializer)
+; CHECK-NEXT:    [[OR:%.*]] = or <vscale x 8 x i16> [[E1]], [[S2]]
+; CHECK-NEXT:    ret <vscale x 8 x i16> [[OR]]
+;
+  %p2 = getelementptr i8, ptr %p1, i32 1
+  %l1 = load <vscale x 8 x i8>, ptr %p1, align 1
+  %l2 = load <vscale x 8 x i8>, ptr %p2, align 1
+  %e1 = zext <vscale x 8 x i8> %l1 to <vscale x 8 x i16>
+  %e2 = zext <vscale x 8 x i8> %l2 to <vscale x 8 x i16>
+  %s2 = shl <vscale x 8 x i16> %e2, shufflevector (<vscale x 8 x i16> insertelement (<vscale x 8 x i16> poison, i16 8, i32 0), <vscale x 8 x i16> poison, <vscale x 8 x i32> zeroinitializer)
+  %or = or <vscale x 8 x i16> %e1, %s2
+  ret <vscale x 8 x i16> %or
+}
Index: llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
===================================================================
--- llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
+++ llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp
@@ -627,6 +627,10 @@
   Value *X;
   Instruction *L1, *L2;
 
+  // Only consider load chains of scalar values.
+  if (isa<VectorType>(V->getType()))
+    return false;
+
   // Go to the last node with loads.
   if (match(V, m_OneUse(m_c_Or(
                    m_Value(X),


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