From 1ca1fcaa5b4c75a65a202badfd5df8240a36ca0f Mon Sep 17 00:00:00 2001

From: "Arch D. Robison" <arch.robison@intel.com>

Date: Mon, 25 Apr 2016 22:22:39 +0000

Subject: [PATCH] Optimize store of "bitcast" from vector to aggregate.

This patch is what was the "instcombine" portion of D14185, with an additional

test added (see julia_pseudovec in test/Transforms/InstCombine/insert-val-extract-elem.ll).

The patch causes instcombine to replace sequences of extractelement-insertvalue-store

that act essentially like a bitcast followed by a store.

Differential review: http://reviews.llvm.org/D14260

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267482 91177308-0d34-0410-b5e6-96231b3b80d8

Alpine maintainer notes:

  - Updated for llvm 3.8.1.

  - This patch replaces llvm-D14260.patch from Julia.

---

 .../InstCombine/InstCombineLoadStoreAlloca.cpp     | 60 ++++++++++++++++++

 .../InstCombine/insert-val-extract-elem.ll         | 74 ++++++++++++++++++++++

 2 files changed, 134 insertions(+)

 create mode 100644 test/Transforms/InstCombine/insert-val-extract-elem.ll

diff --git a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp

index 96f0908..0ee6045 100644

--- a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp

+++ b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp

@@ -913,6 +913,61 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {

   return nullptr;

 }

+/// \brief Look for extractelement/insertvalue sequence that acts like a bitcast.

+///

+/// \returns underlying value that was "cast", or nullptr otherwise.

+///

+/// For example, if we have:

+///

+///     %E0 = extractelement <2 x double> %U, i32 0

+///     %V0 = insertvalue [2 x double] undef, double %E0, 0

+///     %E1 = extractelement <2 x double> %U, i32 1

+///     %V1 = insertvalue [2 x double] %V0, double %E1, 1

+///

+/// and the layout of a <2 x double> is isomorphic to a [2 x double],

+/// then %V1 can be safely approximated by a conceptual "bitcast" of %U.

+/// Note that %U may contain non-undef values where %V1 has undef.

+static Value *likeBitCastFromVector(InstCombiner &IC, Value *V) {

+  Value *U = nullptr;

+  while (auto *IV = dyn_cast<InsertValueInst>(V)) {

+    auto *E = dyn_cast<ExtractElementInst>(IV->getInsertedValueOperand());

+    if (!E)

+      return nullptr;

+    auto *W = E->getVectorOperand();

+    if (!U)

+      U = W;

+    else if (U != W)

+      return nullptr;

+    auto *CI = dyn_cast<ConstantInt>(E->getIndexOperand());

+    if (!CI || IV->getNumIndices() != 1 || CI->getZExtValue() != *IV->idx_begin())

+      return nullptr;

+    V = IV->getAggregateOperand();

+  }

+  if (!isa<UndefValue>(V) ||!U)

+    return nullptr;

+

+  auto *UT = cast<VectorType>(U->getType());

+  auto *VT = V->getType();

+  // Check that types UT and VT are bitwise isomorphic.

+  const auto &DL = IC.getDataLayout();

+  if (DL.getTypeStoreSizeInBits(UT) != DL.getTypeStoreSizeInBits(VT)) {

+    return nullptr;

+  }

+  if (auto *AT = dyn_cast<ArrayType>(VT)) {

+    if (AT->getNumElements() != UT->getNumElements())

+      return nullptr;

+  } else {

+    auto *ST = cast<StructType>(VT);

+    if (ST->getNumElements() != UT->getNumElements())

+      return nullptr;

+    for (const auto *EltT : ST->elements()) {

+      if (EltT != UT->getElementType())

+        return nullptr;

+    }

+  }

+  return U;

+}

+

 /// \brief Combine stores to match the type of value being stored.

 ///

 /// The core idea here is that the memory does not have any intrinsic type and

@@ -924,6 +979,11 @@

     return true;

   }

+  if (Value *U = likeBitCastFromVector(IC, V)) {

+    combineStoreToNewValue(IC, SI, U);

+    return true;

+  }

+

   // FIXME: We should also canonicalize loads of vectors when their elements are

   // cast to other types.

   return false;

diff --git a/test/Transforms/InstCombine/insert-val-extract-elem.ll b/test/Transforms/InstCombine/insert-val-extract-elem.ll

new file mode 100644

index 0000000..db7b403

--- /dev/null

+++ b/test/Transforms/InstCombine/insert-val-extract-elem.ll

@@ -0,0 +1,74 @@

+; RUN: opt -S -instcombine %s | FileCheck %s

+

+; CHECK-LABEL: julia_2xdouble

+; CHECK-NOT: insertvalue

+; CHECK-NOT: extractelement

+; CHECK: store <2 x double>

+define void @julia_2xdouble([2 x double]* sret, <2 x double>*) {

+top:

+  %x = load <2 x double>, <2 x double>* %1

+  %x0 = extractelement <2 x double> %x, i32 0

+  %i0 = insertvalue [2 x double] undef, double %x0, 0

+  %x1 = extractelement <2 x double> %x, i32 1

+  %i1 = insertvalue [2 x double] %i0, double %x1, 1

+  store [2 x double] %i1, [2 x double]* %0, align 4

+  ret void

+}

+

+; Test with two inserts to the same index

+; CHECK-LABEL: julia_2xi64

+; CHECK-NOT: insertvalue

+; CHECK-NOT: extractelement

+; CHECK: store <2 x i64>

+define void @julia_2xi64([2 x i64]* sret, <2 x i64>*) {

+top:

+  %x = load <2 x i64>, <2 x i64>* %1

+  %x0 = extractelement <2 x i64> %x, i32 1

+  %i0 = insertvalue [2 x i64] undef, i64 %x0, 0

+  %x1 = extractelement <2 x i64> %x, i32 1

+  %i1 = insertvalue [2 x i64] %i0, i64 %x1, 1

+  %x2 = extractelement <2 x i64> %x, i32 0

+  %i2 = insertvalue [2 x i64] %i1, i64 %x2, 0

+  store [2 x i64] %i2, [2 x i64]* %0, align 4

+  ret void

+}

+

+; CHECK-LABEL: julia_4xfloat

+; CHECK-NOT: insertvalue

+; CHECK-NOT: extractelement

+; CHECK: store <4 x float>

+define void @julia_4xfloat([4 x float]* sret, <4 x float>*) {

+top:

+  %x = load <4 x float>, <4 x float>* %1

+  %x0 = extractelement <4 x float> %x, i32 0

+  %i0 = insertvalue [4 x float] undef, float %x0, 0

+  %x1 = extractelement <4 x float> %x, i32 1

+  %i1 = insertvalue [4 x float] %i0, float %x1, 1

+  %x2 = extractelement <4 x float> %x, i32 2

+  %i2 = insertvalue [4 x float] %i1, float %x2, 2

+  %x3 = extractelement <4 x float> %x, i32 3

+  %i3 = insertvalue [4 x float] %i2, float %x3, 3

+  store [4 x float] %i3, [4 x float]* %0, align 4

+  ret void

+}

+

+%pseudovec = type { float, float, float, float }

+

+; CHECK-LABEL: julia_pseudovec

+; CHECK-NOT: insertvalue

+; CHECK-NOT: extractelement

+; CHECK: store <4 x float>

+define void @julia_pseudovec(%pseudovec* sret, <4 x float>*) {

+top:

+  %x = load <4 x float>, <4 x float>* %1

+  %x0 = extractelement <4 x float> %x, i32 0

+  %i0 = insertvalue %pseudovec undef, float %x0, 0

+  %x1 = extractelement <4 x float> %x, i32 1

+  %i1 = insertvalue %pseudovec %i0, float %x1, 1

+  %x2 = extractelement <4 x float> %x, i32 2

+  %i2 = insertvalue %pseudovec %i1, float %x2, 2

+  %x3 = extractelement <4 x float> %x, i32 3

+  %i3 = insertvalue %pseudovec %i2, float %x3, 3

+  store %pseudovec %i3, %pseudovec* %0, align 4

+  ret void

+}