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[InstCombine] Fold IntToPtr and PtrToInt into preceding loads.

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Currently we only fold a BitCast into a Load when the BitCast is its
only user.

Do the same for any no-op cast.

Differential Revision: http://reviews.llvm.org/D9152

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238452 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer 2015-05-28 18:39:17 +00:00
parent ef1de3295a
commit 967f6ad3e1
3 changed files with 167 additions and 5 deletions
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15
lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
View File

@ -483,12 +483,17 @@ static Instruction *combineLoadToOperationType(InstCombiner &IC, LoadInst &LI) {
}
// Fold away bit casts of the loaded value by loading the desired type.
// We can do this for BitCastInsts as well as casts from and to pointer types,
// as long as those are noops (i.e., the source or dest type have the same
// bitwidth as the target's pointers).
if (LI.hasOneUse())
if (auto *BC = dyn_cast<BitCastInst>(LI.user_back())) {
LoadInst *NewLoad = combineLoadToNewType(IC, LI, BC->getDestTy());
BC->replaceAllUsesWith(NewLoad);
IC.EraseInstFromFunction(*BC);
return &LI;
if (auto* CI = dyn_cast<CastInst>(LI.user_back())) {
if (CI->isNoopCast(DL)) {
LoadInst *NewLoad = combineLoadToNewType(IC, LI, CI->getDestTy());
CI->replaceAllUsesWith(NewLoad);
IC.EraseInstFromFunction(*CI);
return &LI;
}
}
// FIXME: We should also canonicalize loads of vectors when their elements are

79
test/Transforms/InstCombine/load-bitcast32.ll Normal file
View File

@ -0,0 +1,79 @@
; RUN: opt -instcombine -S < %s | FileCheck %s
target datalayout = "p:32:32:32"
define i64* @test1(i8* %x) {
entry:
; CHECK-LABEL: @test1(
; CHECK: load i64, i64*
; CHECK: ret
%a = bitcast i8* %x to i64*
%b = load i64, i64* %a
%c = inttoptr i64 %b to i64*
ret i64* %c
}
define i32* @test2(i8* %x) {
entry:
; CHECK-LABEL: @test2(
; CHECK: load i32*, i32**
; CHECK: ret
%a = bitcast i8* %x to i32*
%b = load i32, i32* %a
%c = inttoptr i32 %b to i32*
ret i32* %c
}
define i64* @test3(i8* %x) {
entry:
; CHECK-LABEL: @test3(
; CHECK: load i64*, i64**
; CHECK: ret
%a = bitcast i8* %x to i32*
%b = load i32, i32* %a
%c = inttoptr i32 %b to i64*
ret i64* %c
}
define i64 @test4(i8* %x) {
entry:
; CHECK-LABEL: @test4(
; CHECK: load i32, i32*
; CHECK: zext
; CHECK: ret
%a = bitcast i8* %x to i64**
%b = load i64*, i64** %a
%c = ptrtoint i64* %b to i64
ret i64 %c
}
define i32 @test5(i8* %x) {
entry:
; CHECK-LABEL: @test5(
; CHECK: load i32, i32*
; CHECK: ret
%a = bitcast i8* %x to i32**
%b = load i32*, i32** %a
%c = ptrtoint i32* %b to i32
ret i32 %c
}
define i64 @test6(i8* %x) {
entry:
; CHECK-LABEL: @test6(
; CHECK: load i32, i32*
; CHECK: zext
; CHECK: ret
%a = bitcast i8* %x to i32**
%b = load i32*, i32** %a
%c = ptrtoint i32* %b to i64
ret i64 %c
}

78
test/Transforms/InstCombine/load-bitcast64.ll Normal file
View File

@ -0,0 +1,78 @@
; RUN: opt -instcombine -S < %s | FileCheck %s
target datalayout = "p:64:64:64"
define i64* @test1(i8* %x) {
entry:
; CHECK-LABEL: @test1(
; CHECK: load i64*, i64**
; CHECK: ret
%a = bitcast i8* %x to i64*
%b = load i64, i64* %a
%c = inttoptr i64 %b to i64*
ret i64* %c
}
define i32* @test2(i8* %x) {
entry:
; CHECK-LABEL: @test2(
; CHECK: load i32, i32*
; CHECK: ret
%a = bitcast i8* %x to i32*
%b = load i32, i32* %a
%c = inttoptr i32 %b to i32*
ret i32* %c
}
define i64* @test3(i8* %x) {
entry:
; CHECK-LABEL: @test3(
; CHECK: load i32, i32*
; CHECK: ret
%a = bitcast i8* %x to i32*
%b = load i32, i32* %a
%c = inttoptr i32 %b to i64*
ret i64* %c
}
define i64 @test4(i8* %x) {
entry:
; CHECK-LABEL: @test4(
; CHECK: load i64, i64*
; CHECK: ret
%a = bitcast i8* %x to i64**
%b = load i64*, i64** %a
%c = ptrtoint i64* %b to i64
ret i64 %c
}
define i32 @test5(i8* %x) {
entry:
; CHECK-LABEL: @test5(
; CHECK: load i64, i64*
; CHECK: trunc
; CHECK: ret
%a = bitcast i8* %x to i32**
%b = load i32*, i32** %a
%c = ptrtoint i32* %b to i32
ret i32 %c
}
define i64 @test6(i8* %x) {
entry:
; CHECK-LABEL: @test6(
; CHECK: load i64, i64*
; CHECK: ret
%a = bitcast i8* %x to i32**
%b = load i32*, i32** %a
%c = ptrtoint i32* %b to i64
ret i64 %c
}