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[SimplifyCFG] Make the no-jump-tables attribute also disable switch lookup tables 

Differential Revision: https://reviews.llvm.org/D35579

llvm-svn: 309444
This commit is contained in:
Sumanth Gundapaneni 2017-07-28 22:25:40 +00:00
parent f14996b962
commit 8d50a50e98
3 changed files with 86 additions and 3 deletions
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9
llvm/lib/Transforms/Utils/SimplifyCFG.cpp
View File

@ -5151,8 +5151,11 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
const TargetTransformInfo &TTI) { const TargetTransformInfo &TTI) {
assert(SI->getNumCases() > 1 && "Degenerate switch?"); assert(SI->getNumCases() > 1 && "Degenerate switch?");
// Only build lookup table when we have a target that supports it. Function *Fn = SI->getParent()->getParent();
if (!TTI.shouldBuildLookupTables()) // Only build lookup table when we have a target that supports it or the
// attribute is not set.
if (!TTI.shouldBuildLookupTables() ||
(Fn->getFnAttribute("no-jump-tables").getValueAsString() == "true"))
return false; return false;
// FIXME: If the switch is too sparse for a lookup table, perhaps we could // FIXME: If the switch is too sparse for a lookup table, perhaps we could
@ -5333,7 +5336,7 @@ static bool SwitchToLookupTable(SwitchInst *SI, IRBuilder<> &Builder,
// If using a bitmask, use any value to fill the lookup table holes. // If using a bitmask, use any value to fill the lookup table holes.
Constant *DV = NeedMask ? ResultLists[PHI][0].second : DefaultResults[PHI]; Constant *DV = NeedMask ? ResultLists[PHI][0].second : DefaultResults[PHI];
StringRef FuncName = SI->getParent()->getParent()->getName(); StringRef FuncName = Fn->getName();
SwitchLookupTable Table(Mod, TableSize, MinCaseVal, ResultList, DV, DL, SwitchLookupTable Table(Mod, TableSize, MinCaseVal, ResultList, DV, DL,
FuncName); FuncName);

36
llvm/test/Transforms/SimplifyCFG/Hexagon/disable-lookup-table.ll Normal file
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@ -0,0 +1,36 @@
; RUN: opt -S -O2 < %s | FileCheck %s -check-prefix=DISABLE
; RUN: opt -S -hexagon-emit-lookup-tables=true -O2 < %s | FileCheck %s -check-prefix=DISABLE
; RUN: opt -S -hexagon-emit-lookup-tables=false -O2 < %s | FileCheck %s -check-prefix=DISABLE
; The attribute "no-jump-tables"="true" disables the generation of switch generated lookup tables
; DISABLE-NOT: @{{.*}} = private unnamed_addr constant [6 x i32] [i32 9, i32 20, i32 14, i32 22, i32 12, i32 5]
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-unknown--elf"
; Function Attrs: noinline nounwind
define i32 @foo(i32 %c) #0 {
entry:
switch i32 %c, label %sw.default [
i32 42, label %return
i32 43, label %sw.bb1
i32 44, label %sw.bb2
i32 45, label %sw.bb3
i32 46, label %sw.bb4
i32 47, label %sw.bb5
i32 48, label %sw.bb6
]
sw.bb1: br label %return
sw.bb2: br label %return
sw.bb3: br label %return
sw.bb4: br label %return
sw.bb5: br label %return
sw.bb6: br label %return
sw.default: br label %return
return:
%retval.0 = phi i32 [ 15, %sw.default ], [ 1, %sw.bb6 ], [ 62, %sw.bb5 ], [ 27, %sw.bb4 ], [ -1, %sw.bb3 ], [ 0, %sw.bb2 ], [ 123, %sw.bb1 ], [ 55, %entry ]
ret i32 %retval.0
}
attributes #0 = { noinline nounwind "no-jump-tables"="true"}

44
llvm/test/Transforms/SimplifyCFG/disable-lookup-table.ll Normal file
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@ -0,0 +1,44 @@
; RUN: opt < %s -latesimplifycfg -S -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
; In the presence of "-no-jump-tables"="true", late simplifycfg should not
; convert any switch cases to lookup tables.
; CHECK: @switch.table.bar = private unnamed_addr constant [4 x i32] [i32 55, i32 123, i32 0, i32 -1]
; CHECK-LABEL: foo
; CHECK-NOT: @switch.table.foo = private unnamed_addr constant [4 x i32] [i32 55, i32 123, i32 0, i32 -1]
define i32 @foo(i32 %c) "no-jump-tables"="true" {
entry:
switch i32 %c, label %sw.default [
i32 42, label %return
i32 43, label %sw.bb1
i32 44, label %sw.bb2
i32 45, label %sw.bb3
]
sw.bb1: br label %return
sw.bb2: br label %return
sw.bb3: br label %return
sw.default: br label %return
return:
%retval.0 = phi i32 [ 15, %sw.default ], [ -1, %sw.bb3 ], [ 0, %sw.bb2 ], [ 123, %sw.bb1 ], [ 55, %entry ]
ret i32 %retval.0
}
define i32 @bar(i32 %c) {
entry:
switch i32 %c, label %sw.default [
i32 42, label %return
i32 43, label %sw.bb1
i32 44, label %sw.bb2
i32 45, label %sw.bb3
]
sw.bb1: br label %return
sw.bb2: br label %return
sw.bb3: br label %return
sw.default: br label %return
return:
%retval.0 = phi i32 [ 15, %sw.default ], [ -1, %sw.bb3 ], [ 0, %sw.bb2 ], [ 123, %sw.bb1 ], [ 55, %entry ]
ret i32 %retval.0
}