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On 64-bit targets, change 32-bit getelementptr indices to be 64-bit

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getelementptr indices, inserting an explicit cast if necessary.
This helps expose the sign-extension operation to other optimizations.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56133 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2008-09-11 23:06:38 +00:00
parent 3139ff8f7b
commit 4f833d4351
2 changed files with 70 additions and 1 deletions
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13
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -9795,7 +9795,8 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
}
}
// If we are using a wider index than needed for this platform, shrink it
// to what we need. If the incoming value needs a cast instruction,
// to what we need. If narrower, sign-extend it to what we need.
// If the incoming value needs a cast instruction,
// insert it. This explicit cast can make subsequent optimizations more
// obvious.
Value *Op = *i;
@ -9809,6 +9810,16 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
*i = Op;
MadeChange = true;
}
} else if (TD->getTypeSizeInBits(Op->getType()) < TD->getPointerSizeInBits()) {
if (Constant *C = dyn_cast<Constant>(Op)) {
*i = ConstantExpr::getSExt(C, TD->getIntPtrType());
MadeChange = true;
} else {
Op = InsertCastBefore(Instruction::SExt, Op, TD->getIntPtrType(),
GEP);
*i = Op;
MadeChange = true;
}
}
}
}

58
test/Transforms/InstCombine/getelementptr_promote.ll Normal file
View File

@ -0,0 +1,58 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep getelementptr | grep {, i64}
; Instcombine should promote the getelementptr index up to the target's
; pointer size, making the conversion explicit, which helps expose it to
; other optimizations.
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
target triple = "x86_64-apple-darwin8"
define i64 @test(i64* %first, i32 %count) nounwind {
entry:
%first_addr = alloca i64* ; <i64**> [#uses=2]
%count_addr = alloca i32 ; <i32*> [#uses=2]
%retval = alloca i64 ; <i64*> [#uses=2]
%n = alloca i32 ; <i32*> [#uses=5]
%result = alloca i64 ; <i64*> [#uses=4]
%0 = alloca i64 ; <i64*> [#uses=2]
%"alloca point" = bitcast i32 0 to i32 ; <i32> [#uses=0]
store i64* %first, i64** %first_addr
store i32 %count, i32* %count_addr
store i64 0, i64* %result, align 8
store i32 0, i32* %n, align 4
br label %bb1
bb: ; preds = %bb1
%1 = load i64** %first_addr, align 8 ; <i64*> [#uses=1]
%2 = load i32* %n, align 4 ; <i32> [#uses=1]
%3 = bitcast i32 %2 to i32 ; <i64> [#uses=1]
%4 = getelementptr i64* %1, i32 %3 ; <i64*> [#uses=1]
%5 = load i64* %4, align 8 ; <i64> [#uses=1]
%6 = lshr i64 %5, 4 ; <i64> [#uses=1]
%7 = load i64* %result, align 8 ; <i64> [#uses=1]
%8 = add i64 %6, %7 ; <i64> [#uses=1]
store i64 %8, i64* %result, align 8
%9 = load i32* %n, align 4 ; <i32> [#uses=1]
%10 = add i32 %9, 1 ; <i32> [#uses=1]
store i32 %10, i32* %n, align 4
br label %bb1
bb1: ; preds = %bb, %entry
%11 = load i32* %n, align 4 ; <i32> [#uses=1]
%12 = load i32* %count_addr, align 4 ; <i32> [#uses=1]
%13 = icmp slt i32 %11, %12 ; <i1> [#uses=1]
%14 = zext i1 %13 to i8 ; <i8> [#uses=1]
%toBool = icmp ne i8 %14, 0 ; <i1> [#uses=1]
br i1 %toBool, label %bb, label %bb2
bb2: ; preds = %bb1
%15 = load i64* %result, align 8 ; <i64> [#uses=1]
store i64 %15, i64* %0, align 8
%16 = load i64* %0, align 8 ; <i64> [#uses=1]
store i64 %16, i64* %retval, align 8
br label %return
return: ; preds = %bb2
%retval3 = load i64* %retval ; <i64> [#uses=1]
ret i64 %retval3
}