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fix PR6623: when optimizing for size, don't inline memcpy/memsets

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that are too large.  This causes the freebsd bootloader to be too
large apparently.

It's unclear if this should be an -Os or -Oz thing.  Thoughts welcome.

llvm-svn: 105228
This commit is contained in:
Chris Lattner 2010-05-31 17:30:14 +00:00
parent e8b65c0352
commit 14bf35ae45
2 changed files with 39 additions and 0 deletions
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9
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
View File

@ -3266,6 +3266,15 @@ static bool FindOptimalMemOpLowering(std::vector<EVT> &MemOps,
if (VT.bitsGT(LVT))
VT = LVT;
}
// If we're optimizing for size, and there is a limit, bump the maximum number
// of operations inserted down to 4. This is a wild guess that approximates
// the size of a call to memcpy or memset (3 arguments + call).
if (Limit != ~0U) {
const Function *F = DAG.getMachineFunction().getFunction();
if (F->hasFnAttr(Attribute::OptimizeForSize))
Limit = 4;
}
unsigned NumMemOps = 0;
while (Size != 0) {

30
test/CodeGen/X86/memcpy.ll
View File

@ -25,3 +25,33 @@ entry:
; CHECK: memcpy
}
; Large constant memcpy's should lower to a call when optimizing for size.
; PR6623
define void @test3(i8* nocapture %A, i8* nocapture %B) nounwind optsize noredzone {
entry:
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %A, i8* %B, i64 64, i32 1, i1 false)
ret void
; CHECK: test3:
; CHECK: memcpy
}
; Large constant memcpy's should be inlined when not optimizing for size.
define void @test4(i8* nocapture %A, i8* nocapture %B) nounwind noredzone {
entry:
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %A, i8* %B, i64 64, i32 1, i1 false)
ret void
; CHECK: test4:
; CHECK: movq
; CHECK: movq
; CHECK: movq
; CHECK: movq
; CHECK: movq
; CHECK: movq
; CHECK: movq
; CHECK: movq
; CHECK: movq
; CHECK: movq
; CHECK: movq
; CHECK: movq
}