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Teach instcombine to promote alloca array sizes.

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llvm-svn: 104945
This commit is contained in:
Dan Gohman 2010-05-28 15:09:00 +00:00
parent bab79afa29
commit 22d22caaed
2 changed files with 29 additions and 3 deletions
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12
lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
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@ -22,6 +22,18 @@ using namespace llvm;
STATISTIC(NumDeadStore, "Number of dead stores eliminated");
Instruction *InstCombiner::visitAllocaInst(AllocaInst &AI) {
// Ensure that the alloca array size argument has type intptr_t, so that
// any casting is exposed early.
if (TD) {
const Type *IntPtrTy = TD->getIntPtrType(AI.getContext());
if (AI.getArraySize()->getType() != IntPtrTy) {
Value *V = Builder->CreateIntCast(AI.getArraySize(),
IntPtrTy, false);
AI.setOperand(0, V);
return &AI;
}
}
// Convert: alloca Ty, C - where C is a constant != 1 into: alloca [C x Ty], 1
if (AI.isArrayAllocation()) { // Check C != 1
if (const ConstantInt *C = dyn_cast<ConstantInt>(AI.getArraySize())) {

20
test/Transforms/InstCombine/alloca.ll
View File

@ -1,12 +1,13 @@
; Zero byte allocas should be deleted.
target datalayout = "E-p:64:64:64-a0:0:8-f32:32:32-f64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-v64:64:64-v128:128:128"
; RUN: opt < %s -instcombine -S | \
; RUN: not grep alloca
; RUN: opt < %s -instcombine -S | FileCheck %s
; END.
declare void @use(...)
; Zero byte allocas should be deleted.
; CHECK: @test
; CHECK-NOT: alloca
define void @test() {
%X = alloca [0 x i32] ; <[0 x i32]*> [#uses=1]
call void (...)* @use( [0 x i32]* %X )
@ -17,12 +18,18 @@ define void @test() {
ret void
}
; Zero byte allocas should be deleted.
; CHECK: @test2
; CHECK-NOT: alloca
define void @test2() {
%A = alloca i32 ; <i32*> [#uses=1]
store i32 123, i32* %A
ret void
}
; Zero byte allocas should be deleted.
; CHECK: @test3
; CHECK-NOT: alloca
define void @test3() {
%A = alloca { i32 } ; <{ i32 }*> [#uses=1]
%B = getelementptr { i32 }* %A, i32 0, i32 0 ; <i32*> [#uses=1]
@ -30,3 +37,10 @@ define void @test3() {
ret void
}
; CHECK: @test4
; CHECK: = zext i32 %n to i64
; CHECK: %A = alloca i32, i64 %
define i32* @test4(i32 %n) {
%A = alloca i32, i32 %n
ret i32* %A
}