[GlobalOpt] Ignore only loaded / only stored global parts in global SRA heuristic

When limiting the number of parts we split a global into, ignore
any parts that are either only loaded or only stored, because we
expect these to be optimized away after SRA.

Differential Revision: https://reviews.llvm.org/D129857

diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index 435f38f55f7cc0b88fd8250f295d514377014291..bbe9f878973f0ecc5a3327359d00e6d1b9d35c15 100644 (file)
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -335,8 +335,12 @@ static bool CleanupConstantGlobalUsers(GlobalVariable *GV,
   return Changed;
 }
 
+/// Part of the global at a specific offset, which is only accessed through
+/// loads and stores with the given type.
 struct GlobalPart {
   Type *Ty;
+  bool IsLoaded = false;
+  bool IsStored = false;
 };
 
 /// Look at all uses of the global and determine which (offset, type) pairs it
@@ -385,6 +389,8 @@ static bool collectSRATypes(DenseMap<uint64_t, GlobalPart> &Parts,
       if (isa<ScalableVectorType>(Ty))
         return false;
 
+      It->second.IsLoaded |= isa<LoadInst>(V);
+      It->second.IsStored |= isa<StoreInst>(V);
       continue;
     }
 
@@ -471,8 +477,13 @@ static GlobalVariable *SRAGlobal(GlobalVariable *GV, const DataLayout &DL) {
   if (Parts.size() == 1 && Parts.begin()->second.Ty == GV->getValueType())
     return nullptr;
 
-  // Don't perform SRA if we would have to split into many globals.
-  if (Parts.size() > 16)
+  // Don't perform SRA if we would have to split into many globals. Ignore
+  // parts that are either only loaded or only stored, because we expect them
+  // to be optimized away.
+  unsigned NumParts = count_if(Parts, [](const auto &Pair) {
+    return Pair.second.IsLoaded && Pair.second.IsStored;
+  });
+  if (NumParts > 16)
     return nullptr;
 
   // Sort by offset.

diff --git a/llvm/test/Transforms/GlobalOpt/sra-many-stores.ll b/llvm/test/Transforms/GlobalOpt/sra-many-stores.ll
index 2dec7e0e0a4d39176cef7cc195121904d15ebdc0..689ef6d7762057cf82ff8ee9fed86a669c7c7c50 100644 (file)
--- a/llvm/test/Transforms/GlobalOpt/sra-many-stores.ll
+++ b/llvm/test/Transforms/GlobalOpt/sra-many-stores.ll
@@ -7,17 +7,12 @@
 
 
 ;.
-; CHECK: @[[GLOBAL:[a-zA-Z0-9_$"\\.-]+]] = internal unnamed_addr global [[STRUCT_WIDGET:%.*]] zeroinitializer
-; CHECK: @[[GLOBAL_ARRAY_IN_STRUCT:[a-zA-Z0-9_$"\\.-]+]] = internal unnamed_addr global [[STRUCT_WITH_ARRAY:%.*]] zeroinitializer
-; CHECK: @[[GLOBAL_ARRAY:[a-zA-Z0-9_$"\\.-]+]] = internal unnamed_addr global [100 x i64] zeroinitializer
 ; CHECK: @[[A:[a-zA-Z0-9_$"\\.-]+]] = global i8 0, align 4
-; CHECK: @[[B:[a-zA-Z0-9_$"\\.-]+]] = internal unnamed_addr global [[STRUCT_20I8:%.*]] { i8 4, i8 4, i8 4, i8 5, i8 4, i8 4, i8 4, i8 4, i8 4, i8 4, i8 5, i8 4, i8 4, i8 4, i8 4, i8 4, i8 4, i8 4, i8 4, i8 4 }
 ; CHECK: @[[GLOBAL_20PTR:[a-zA-Z0-9_$"\\.-]+]] = internal unnamed_addr global [[STRUCT_20PTR:%.*]] zeroinitializer
 ; CHECK: @[[C:[a-zA-Z0-9_$"\\.-]+]] = global ptr null
 ;.
 define internal void @read_struct() {
 ; CHECK-LABEL: @read_struct(
-; CHECK-NEXT:    [[TMP:%.*]] = load ptr, ptr getelementptr inbounds ([[STRUCT_WIDGET:%.*]], ptr @global, i64 0, i32 16), align 8
 ; CHECK-NEXT:    ret void
 ;
   %tmp = load ptr, ptr getelementptr inbounds (%struct.widget, ptr @global, i64 0, i32 16), align 8
@@ -26,22 +21,6 @@ define internal void @read_struct() {
 
 define void @write_struct() {
 ; CHECK-LABEL: @write_struct(
-; CHECK-NEXT:    store ptr null, ptr @global, align 8
-; CHECK-NEXT:    store ptr null, ptr getelementptr inbounds ([[STRUCT_WIDGET:%.*]], ptr @global, i64 0, i32 1), align 8
-; CHECK-NEXT:    store ptr null, ptr getelementptr inbounds ([[STRUCT_WIDGET]], ptr @global, i64 0, i32 2), align 8
-; CHECK-NEXT:    store ptr null, ptr getelementptr inbounds ([[STRUCT_WIDGET]], ptr @global, i64 0, i32 3), align 8
-; CHECK-NEXT:    store ptr null, ptr getelementptr inbounds ([[STRUCT_WIDGET]], ptr @global, i64 0, i32 4), align 8
-; CHECK-NEXT:    store ptr null, ptr getelementptr inbounds ([[STRUCT_WIDGET]], ptr @global, i64 0, i32 5), align 8
-; CHECK-NEXT:    store ptr null, ptr getelementptr inbounds ([[STRUCT_WIDGET]], ptr @global, i64 0, i32 6), align 8
-; CHECK-NEXT:    store ptr null, ptr getelementptr inbounds ([[STRUCT_WIDGET]], ptr @global, i64 0, i32 7), align 8
-; CHECK-NEXT:    store ptr null, ptr getelementptr inbounds ([[STRUCT_WIDGET]], ptr @global, i64 0, i32 8), align 8
-; CHECK-NEXT:    store ptr null, ptr getelementptr inbounds ([[STRUCT_WIDGET]], ptr @global, i64 0, i32 9), align 8
-; CHECK-NEXT:    store ptr null, ptr getelementptr inbounds ([[STRUCT_WIDGET]], ptr @global, i64 0, i32 10), align 8
-; CHECK-NEXT:    store ptr null, ptr getelementptr inbounds ([[STRUCT_WIDGET]], ptr @global, i64 0, i32 11), align 8
-; CHECK-NEXT:    store ptr null, ptr getelementptr inbounds ([[STRUCT_WIDGET]], ptr @global, i64 0, i32 12), align 8
-; CHECK-NEXT:    store ptr null, ptr getelementptr inbounds ([[STRUCT_WIDGET]], ptr @global, i64 0, i32 13), align 8
-; CHECK-NEXT:    store ptr null, ptr getelementptr inbounds ([[STRUCT_WIDGET]], ptr @global, i64 0, i32 14), align 8
-; CHECK-NEXT:    store ptr null, ptr getelementptr inbounds ([[STRUCT_WIDGET]], ptr @global, i64 0, i32 15), align 8
 ; CHECK-NEXT:    tail call fastcc void @read_struct()
 ; CHECK-NEXT:    ret void
 ;
@@ -72,7 +51,6 @@ define void @write_struct() {
 
 define internal void @read_non_array_field() {
 ; CHECK-LABEL: @read_non_array_field(
-; CHECK-NEXT:    [[TMP:%.*]] = load i64, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY:%.*]], ptr @global.array_in_struct, i64 0, i32 1), align 8
 ; CHECK-NEXT:    ret void
 ;
   %tmp = load i64, ptr getelementptr inbounds (%struct.with.array, ptr @global.array_in_struct, i64 0, i32 1), align 8
@@ -81,22 +59,6 @@ define internal void @read_non_array_field() {
 
 define void @store_to_struct_array() {
 ; CHECK-LABEL: @store_to_struct_array(
-; CHECK-NEXT:    store i64 0, ptr @global.array_in_struct, align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY:%.*]], ptr @global.array_in_struct, i64 0, i32 0, i32 1), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY]], ptr @global.array_in_struct, i64 0, i32 0, i32 2), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY]], ptr @global.array_in_struct, i64 0, i32 0, i32 3), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY]], ptr @global.array_in_struct, i64 0, i32 0, i32 4), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY]], ptr @global.array_in_struct, i64 0, i32 0, i32 5), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY]], ptr @global.array_in_struct, i64 0, i32 0, i32 6), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY]], ptr @global.array_in_struct, i64 0, i32 0, i32 7), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY]], ptr @global.array_in_struct, i64 0, i32 0, i32 8), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY]], ptr @global.array_in_struct, i64 0, i32 0, i32 9), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY]], ptr @global.array_in_struct, i64 0, i32 0, i32 10), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY]], ptr @global.array_in_struct, i64 0, i32 0, i32 11), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY]], ptr @global.array_in_struct, i64 0, i32 0, i32 12), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY]], ptr @global.array_in_struct, i64 0, i32 0, i32 13), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY]], ptr @global.array_in_struct, i64 0, i32 0, i32 14), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([[STRUCT_WITH_ARRAY]], ptr @global.array_in_struct, i64 0, i32 0, i32 15), align 8
 ; CHECK-NEXT:    tail call fastcc void @read_non_array_field()
 ; CHECK-NEXT:    ret void
 ;
@@ -124,7 +86,6 @@ define void @store_to_struct_array() {
 
 define internal void @read_array() {
 ; CHECK-LABEL: @read_array(
-; CHECK-NEXT:    [[TMP:%.*]] = load i64, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 99), align 8
 ; CHECK-NEXT:    ret void
 ;
   %tmp = load i64, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 99), align 8
@@ -133,22 +94,6 @@ define internal void @read_array() {
 
 define void @store_to_array() {
 ; CHECK-LABEL: @store_to_array(
-; CHECK-NEXT:    store i64 0, ptr @global.array, align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 1), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 2), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 3), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 4), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 5), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 6), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 7), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 8), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 9), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 10), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 11), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 12), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 13), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 14), align 8
-; CHECK-NEXT:    store i64 0, ptr getelementptr inbounds ([100 x i64], ptr @global.array, i64 0, i32 15), align 8
 ; CHECK-NEXT:    tail call fastcc void @read_array()
 ; CHECK-NEXT:    ret void
 ;
@@ -179,41 +124,23 @@ define void @store_to_array() {
 
 define void @test_single_write_to_global_b() {
 ; CHECK-LABEL: @test_single_write_to_global_b(
-; CHECK-NEXT:    store i8 0, ptr getelementptr inbounds ([[STRUCT_20I8:%.*]], ptr @b, i64 0, i32 1), align 1
-; CHECK-NEXT:    [[I3:%.*]] = load i8, ptr @b, align 16
-; CHECK-NEXT:    store volatile i8 [[I3]], ptr @a, align 4
-; CHECK-NEXT:    [[I4:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 2), align 2
-; CHECK-NEXT:    store volatile i8 [[I4]], ptr @a, align 4
-; CHECK-NEXT:    [[I5:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 3), align 1
-; CHECK-NEXT:    store volatile i8 [[I5]], ptr @a, align 4
-; CHECK-NEXT:    [[I6:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 4), align 4
-; CHECK-NEXT:    store volatile i8 [[I6]], ptr @a, align 4
-; CHECK-NEXT:    [[I7:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 5), align 1
-; CHECK-NEXT:    store volatile i8 [[I7]], ptr @a, align 4
-; CHECK-NEXT:    [[I8:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 7), align 1
-; CHECK-NEXT:    store volatile i8 [[I8]], ptr @a, align 4
-; CHECK-NEXT:    [[I9:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 8), align 8
-; CHECK-NEXT:    store volatile i8 [[I9]], ptr @a, align 4
-; CHECK-NEXT:    [[I10:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 9), align 1
-; CHECK-NEXT:    store volatile i8 [[I10]], ptr @a, align 4
-; CHECK-NEXT:    [[I11:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 10), align 2
-; CHECK-NEXT:    store volatile i8 [[I11]], ptr @a, align 4
-; CHECK-NEXT:    [[I12:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 11), align 1
-; CHECK-NEXT:    store volatile i8 [[I12]], ptr @a, align 4
-; CHECK-NEXT:    [[I13:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 12), align 4
-; CHECK-NEXT:    store volatile i8 [[I13]], ptr @a, align 4
-; CHECK-NEXT:    [[I14:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 13), align 1
-; CHECK-NEXT:    store volatile i8 [[I14]], ptr @a, align 4
-; CHECK-NEXT:    [[I15:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 14), align 2
-; CHECK-NEXT:    store volatile i8 [[I15]], ptr @a, align 4
-; CHECK-NEXT:    [[I16:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 15), align 1
-; CHECK-NEXT:    store volatile i8 [[I16]], ptr @a, align 4
-; CHECK-NEXT:    [[I17:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 16), align 16
-; CHECK-NEXT:    store volatile i8 [[I17]], ptr @a, align 4
-; CHECK-NEXT:    [[I18:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 17), align 1
-; CHECK-NEXT:    store volatile i8 [[I18]], ptr @a, align 4
-; CHECK-NEXT:    [[I19:%.*]] = load i8, ptr getelementptr inbounds ([[STRUCT_20I8]], ptr @b, i64 0, i32 18), align 2
-; CHECK-NEXT:    store volatile i8 [[I19]], ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 4, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 4, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 5, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 4, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 4, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 4, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 4, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 4, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 5, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 4, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 4, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 4, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 4, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 4, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 4, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 4, ptr @a, align 4
+; CHECK-NEXT:    store volatile i8 4, ptr @a, align 4
 ; CHECK-NEXT:    ret void
 ;
   store i8 0, ptr getelementptr inbounds (%struct.20i8, ptr @b, i64 0, i32 1), align 1