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670458b3be
Weird code sometimes uses pointer constants other than null. This patch
teaches SimplifyCFG to build switch instructions in those cases.
Code like this:
void f(const char *x) {
if (!x)
puts("null");
else if ((uintptr_t)x == 1)
puts("one");
else if (x == (char*)2 || x == (char*)3)
puts("two");
else if ((intptr_t)x == 4)
puts("four");
else
puts(x);
}
Now becomes a switch:
define void @f(i8* %x) nounwind ssp {
entry:
%magicptr23 = ptrtoint i8* %x to i64 ; <i64> [#uses=1]
switch i64 %magicptr23, label %if.else16 [
i64 0, label %if.then
i64 1, label %if.then2
i64 2, label %if.then9
i64 3, label %if.then9
i64 4, label %if.then14
]
Note that LLVM's own DenseMap uses magic pointers.
llvm-svn: 95439
77 lines
3.1 KiB
LLVM
77 lines
3.1 KiB
LLVM
; Test that simplifycfg can create switch instructions from constant pointers.
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;
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; RUN: opt < %s -simplifycfg -S | FileCheck %s
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; CHECK: switch i64 %magicptr
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; CHECK: i64 0, label
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; CHECK: i64 1, label
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; CHECK: i64 2, label
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; CHECK: i64 3, label
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; CHECK: i64 4, label
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; CHECK-NOT: br
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; CHECK: }
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
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target triple = "x86_64-apple-darwin10.0.0"
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@.str = private constant [5 x i8] c"null\00" ; <[5 x i8]*> [#uses=2]
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@.str1 = private constant [4 x i8] c"one\00" ; <[4 x i8]*> [#uses=2]
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@.str2 = private constant [4 x i8] c"two\00" ; <[4 x i8]*> [#uses=2]
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@.str3 = private constant [5 x i8] c"four\00" ; <[5 x i8]*> [#uses=2]
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define void @f(i8* %x) nounwind ssp {
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entry:
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%tobool = icmp eq i8* %x, null ; <i1> [#uses=1]
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br i1 %tobool, label %if.then, label %if.else
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if.then: ; preds = %entry
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%call = call i32 @puts(i8* getelementptr inbounds ([5 x i8]* @.str, i64 0, i64 0)) nounwind ; <i32> [#uses=0]
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br label %if.end21
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if.else: ; preds = %entry
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%cmp = icmp eq i8* %x, inttoptr (i64 1 to i8*) ; <i1> [#uses=1]
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br i1 %cmp, label %if.then2, label %if.else4
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if.then2: ; preds = %if.else
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%call3 = call i32 @puts(i8* getelementptr inbounds ([4 x i8]* @.str1, i64 0, i64 0)) nounwind ; <i32> [#uses=0]
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br label %if.end20
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if.else4: ; preds = %if.else
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%cmp6 = icmp eq i8* %x, inttoptr (i64 2 to i8*) ; <i1> [#uses=1]
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br i1 %cmp6, label %if.then9, label %lor.lhs.false
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lor.lhs.false: ; preds = %if.else4
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%cmp8 = icmp eq i8* %x, inttoptr (i64 3 to i8*) ; <i1> [#uses=1]
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br i1 %cmp8, label %if.then9, label %if.else11
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if.then9: ; preds = %lor.lhs.false, %if.else4
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%call10 = call i32 @puts(i8* getelementptr inbounds ([4 x i8]* @.str2, i64 0, i64 0)) nounwind ; <i32> [#uses=0]
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br label %if.end19
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if.else11: ; preds = %lor.lhs.false
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%cmp13 = icmp eq i8* %x, inttoptr (i64 4 to i8*) ; <i1> [#uses=1]
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br i1 %cmp13, label %if.then14, label %if.else16
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if.then14: ; preds = %if.else11
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%call15 = call i32 @puts(i8* getelementptr inbounds ([5 x i8]* @.str3, i64 0, i64 0)) nounwind ; <i32> [#uses=0]
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br label %if.end
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if.else16: ; preds = %if.else11
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%call18 = call i32 @puts(i8* %x) nounwind ; <i32> [#uses=0]
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br label %if.end
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if.end: ; preds = %if.else16, %if.then14
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br label %if.end19
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if.end19: ; preds = %if.end, %if.then9
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br label %if.end20
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if.end20: ; preds = %if.end19, %if.then2
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br label %if.end21
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if.end21: ; preds = %if.end20, %if.then
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ret void
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}
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declare i32 @puts(i8*)
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