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Add comments and test case for [X86TTI] Make constant base pointers for GetElementPtr opaque (r204739). 

llvm-svn: 205468
This commit is contained in:
Juergen Ributzka 2014-04-02 21:45:36 +00:00
parent 7ad0b88396
commit 27435b3b8a
2 changed files with 27 additions and 0 deletions
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3
llvm/lib/Target/X86/X86TargetTransformInfo.cpp
View File

@ -915,6 +915,9 @@ unsigned X86TTI::getIntImmCost(unsigned Opcode, unsigned Idx, const APInt &Imm,
switch (Opcode) { switch (Opcode) {
default: return TCC_Free; default: return TCC_Free;
case Instruction::GetElementPtr: case Instruction::GetElementPtr:
// Always hoist the base address of a GetElementPtr. This prevents the
// creation of new constants for every base constant that gets constant
// folded with the offset.
if (Idx == 0) if (Idx == 0)
return 2 * TCC_Basic; return 2 * TCC_Basic;
return TCC_Free; return TCC_Free;

24
llvm/test/Transforms/ConstantHoisting/X86/const-base-addr.ll Normal file
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@ -0,0 +1,24 @@
; RUN: opt -S -consthoist < %s | FileCheck %s
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.9.0"
%T = type { i32, i32, i32, i32 }
; Test if even cheap base addreses are hoisted.
define i32 @test1() nounwind {
; CHECK-LABEL: @test1
; CHECK: %const = bitcast i32 12345678 to i32
; CHECK: %1 = inttoptr i32 %const to %T*
; CHECK: %addr1 = getelementptr %T* %1, i32 0, i32 1
%addr1 = getelementptr %T* inttoptr (i32 12345678 to %T*), i32 0, i32 1
%tmp1 = load i32* %addr1
%addr2 = getelementptr %T* inttoptr (i32 12345678 to %T*), i32 0, i32 2
%tmp2 = load i32* %addr2
%addr3 = getelementptr %T* inttoptr (i32 12345678 to %T*), i32 0, i32 3
%tmp3 = load i32* %addr3
%tmp4 = add i32 %tmp1, %tmp2
%tmp5 = add i32 %tmp3, %tmp4
ret i32 %tmp5
}