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[Hexagon] Only use restore functions for single register at -Oz

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llvm-svn: 264581
This commit is contained in:
Krzysztof Parzyszek 2016-03-28 14:52:21 +00:00
parent fc357e83ee
commit bd3e938f88
2 changed files with 53 additions and 0 deletions
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11
lib/Target/Hexagon/HexagonFrameLowering.cpp
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@ -2218,7 +2218,18 @@ bool HexagonFrameLowering::useRestoreFunction(MachineFunction &MF,
const CSIVect &CSI) const {
if (shouldInlineCSR(MF, CSI))
return false;
// The restore functions do a bit more than just restoring registers.
// The non-returning versions will go back directly to the caller's
// caller, others will clean up the stack frame in preparation for
// a tail call. Using them can still save code size even if only one
// register is getting restores. Make the decision based on -Oz:
// using -Os will use inline restore for a single register.
if (isMinSize(MF))
return true;
unsigned NumCSI = CSI.size();
if (NumCSI <= 1)
return false;
unsigned Threshold = isOptSize(MF) ? SpillFuncThresholdOs-1
: SpillFuncThreshold;
return Threshold < NumCSI;

42
test/CodeGen/Hexagon/restore-single-reg.ll Normal file
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@ -0,0 +1,42 @@
; RUN: llc -march=hexagon < %s | FileCheck %s
target datalayout = "e-m:e-p:32:32:32-a:0-n16:32-i64:64:64-i32:32:32-i16:16:16-i1:8:8-f32:32:32-f64:64:64-v32:32:32-v64:64:64-v512:512:512-v1024:1024:1024-v2048:2048:2048"
target triple = "hexagon"
; Generate the inline restore for single register pair for functions
; with "optsize" attribute.
; CHECK-LABEL: fred_os
; CHECK-DAG: memd{{.*}} = r17:16
; CHECK-DAG: r17:16 = memd{{.*}}
; CHECK-DAG: deallocframe
; CHECK-NOT: call __restore
define i32 @fred_os(i32 %x) #0 {
entry:
%call = tail call i32 @foo(i32 %x) #2
%call1 = tail call i32 @bar(i32 %x, i32 %call) #2
ret i32 %call1
}
; Generate the restoring call for single register pair for functions
; with "minsize" attribute.
; CHECK-LABEL: fred_oz
; CHECK-DAG: memd{{.*}} = r17:16
; CHECK-NOT: r17:16 = memd{{.*}}
; CHECK-DAG: call __restore
define i32 @fred_oz(i32 %x) #1 {
entry:
%call = tail call i32 @foo(i32 %x) #2
%call1 = tail call i32 @bar(i32 %x, i32 %call) #2
ret i32 %call1
}
declare i32 @foo(i32) #2
declare i32 @bar(i32, i32) #2
attributes #0 = { nounwind optsize "disable-tail-calls"="false" }
attributes #1 = { nounwind minsize "disable-tail-calls"="false" }
attributes #2 = { nounwind optsize }