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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
+}
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