Insert switch tables into the program memory address space (2/4)

[dylanmckay]

Summary

This means that on Harvard architectures like AVR, we will now place
these tables into program memory, rather than RAM.

Full patchset

• Add program address space to data layout D37052
• Insert switch tables into the program memory address space D37053
• Require address space to be specified when creating functions D37054
• [clang] Require address space to be specified when creating functions D37057

[dylanmckay]

Remove a mistakenly-committed file

[dylanmckay]

I will focus on setting address space on Functions - later on I will look at switch tables

lib/Transforms/Utils/SimplifyCFG.cpp

SwitchLookupTable::SwitchLookupTable(
   }
 
   // Store the table in an array.
   ArrayType *ArrayTy = ArrayType::get(ValueType, TableSize);
   Constant *Initializer = ConstantArray::get(ArrayTy, TableContents);
 
   Array = new GlobalVariable(M, ArrayTy, /*constant=*/true,
                              GlobalVariable::PrivateLinkage, Initializer,
-                             "switch.table." + FuncName);
+                             "switch.table." + FuncName,
+                             /*InsertBefore=*/nullptr,
+                             GlobalValue::NotThreadLocal,
+                             DL.getProgramAddressSpace());
   Array->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
   Kind = ArrayKind;
 }
 
 Value *SwitchLookupTable::BuildLookup(Value *Index, IRBuilder<> &Builder) {
   switch (Kind) {
   case SingleValueKind:
     return SingleValue;

test/CodeGen/AVR/switch-lookup-table-in-progmem-space.ll

+; RUN: opt -S -mtriple=avr -latesimplifycfg < %s | FileCheck %s
+
+target datalayout = "e-p:16:16:16-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-n8-P1"
+
+; Switch lookup tables should be placed in program memory (address space 1).
+
+%MyType = type { i8, [0 x i8], [0 x i8] }
+
+define i8 @foo(i8 %arg) {
+start:
+  %_0 = alloca %MyType
+
+; CHECK: @switch.table.foo = {{.*}}addrspace(1) constant {{.*}}
+  switch i8 %arg, label %bb7 [
+    i8 0, label %bb1
+    i8 1, label %bb2
+    i8 2, label %bb3
+    i8 3, label %bb4
+    i8 4, label %bb5
+    i8 14, label %bb6
+  ]
+
+bb1:                                              ; preds = %start
+  %tmp = getelementptr inbounds %MyType, %MyType* %_0, i32 0, i32 0
+  store i8 1, i8* %tmp
+  br label %bb8
+
+bb2:                                              ; preds = %start
+  %tmp1 = getelementptr inbounds %MyType, %MyType* %_0, i32 0, i32 0
+  store i8 1, i8* %tmp1
+  br label %bb8
+
+bb3:                                              ; preds = %start
+  %tmp2 = getelementptr inbounds %MyType, %MyType* %_0, i32 0, i32 0
+  store i8 1, i8* %tmp2
+  br label %bb8
+
+bb4:                                              ; preds = %start
+  %tmp3 = getelementptr inbounds %MyType, %MyType* %_0, i32 0, i32 0
+  store i8 1, i8* %tmp3
+  br label %bb8
+
+bb5:                                              ; preds = %start
+  %tmp4 = getelementptr inbounds %MyType, %MyType* %_0, i32 0, i32 0
+  store i8 1, i8* %tmp4
+  br label %bb8
+
+bb6:                                              ; preds = %start
+  %tmp5 = getelementptr inbounds %MyType, %MyType* %_0, i32 0, i32 0
+  store i8 1, i8* %tmp5
+  br label %bb8
+
+bb7:                                              ; preds = %start
+  %tmp6 = getelementptr inbounds %MyType, %MyType* %_0, i32 0, i32 0
+  store i8 0, i8* %tmp6
+  br label %bb8
+
+bb8:                                              ; preds = %bb7, %bb6, %bb5, %bb4, %bb3, %bb2, %bb1
+  %tmp7 = bitcast %MyType* %_0 to i8*
+  %tmp8 = load i8, i8* %tmp7, align 1
+  ret i8 %tmp8
+}