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PR for llvm/llvm-project#57021 #79

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Aug 12, 2022
Merged

PR for llvm/llvm-project#57021 #79

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8 changes: 6 additions & 2 deletions llvm/lib/Transforms/Utils/RelLookupTableConverter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -57,11 +57,15 @@ static bool shouldConvertToRelLookupTable(Module &M, GlobalVariable &GV) {
return false;

ConstantArray *Array = dyn_cast<ConstantArray>(GV.getInitializer());
// If values are not pointers, do not generate a relative lookup table.
if (!Array || !Array->getType()->getElementType()->isPointerTy())
if (!Array)
return false;

// If values are not 64-bit pointers, do not generate a relative lookup table.
const DataLayout &DL = M.getDataLayout();
Type *ElemType = Array->getType()->getElementType();
if (!ElemType->isPointerTy() || DL.getPointerTypeSizeInBits(ElemType) != 64)
return false;

for (const Use &Op : Array->operands()) {
Constant *ConstOp = cast<Constant>(&Op);
GlobalValue *GVOp;
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23 changes: 23 additions & 0 deletions llvm/test/Transforms/RelLookupTableConverter/X86/gnux32.ll
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@@ -0,0 +1,23 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -passes=rel-lookup-table-converter -relocation-model=pic -S | FileCheck %s
; REQUIRES: x86-registered-target

target datalayout = "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnux32"

@a = internal constant i32 0, align 4
@b = internal constant i32 0, align 4
@c = internal constant i32 0, align 4

@table = private unnamed_addr constant [3 x ptr] [ptr @a, ptr @b, ptr @c]

define ptr @test(i32 %cond) {
; CHECK-LABEL: @test(
; CHECK-NEXT: [[SWITCH_GEP:%.*]] = getelementptr inbounds [3 x ptr], ptr @table, i32 0, i32 [[COND:%.*]]
; CHECK-NEXT: [[SWITCH_LOAD:%.*]] = load ptr, ptr [[SWITCH_GEP]], align 8
; CHECK-NEXT: ret ptr [[SWITCH_LOAD]]
;
%switch.gep = getelementptr inbounds [3 x ptr], ptr @table, i32 0, i32 %cond
%switch.load = load ptr, ptr %switch.gep, align 8
ret ptr %switch.load
}