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Remove/fix invalid README entries. The well thought out strcpy function doesn't return a pointer to the end of the string.

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llvm-svn: 122496
This commit is contained in:
Benjamin Kramer 2010-12-23 15:32:07 +00:00
parent b21118c91b
commit 0a0e2c55c4
1 changed files with 2 additions and 21 deletions
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23
lib/Target/README.txt
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@ -697,7 +697,7 @@ implementations of ceil/floor/rint.
Consider:
int test() {
long long input[8] = {1,1,1,1,1,1,1,1};
long long input[8] = {1,0,1,0,1,0,1,0};
foo(input);
}
@ -1432,14 +1432,7 @@ Those should be turned into a switch.
This is interesting for a couple reasons. First, in this:
%3073 = call i8* @strcpy(i8* %3072, i8* %3071) nounwind
%strlen = call i32 @strlen(i8* %3072)
The strlen could be replaced with: %strlen = sub %3072, %3073, because the
strcpy call returns a pointer to the end of the string. Based on that, the
endptr GEP just becomes equal to 3073, which eliminates a strlen call and GEP.
Second, the memcpy+strlen strlen can be replaced with:
The memcpy+strlen strlen can be replaced with:
%3074 = call i32 @strlen([5 x i8]* @"\01LC42") nounwind readonly
@ -1515,18 +1508,6 @@ This pattern repeats several times, basically doing:
//===---------------------------------------------------------------------===//
186.crafty also contains this code:
%1906 = call i32 @strlen(i8* getelementptr ([32 x i8]* @pgn_event, i32 0,i32 0))
%1907 = getelementptr [32 x i8]* @pgn_event, i32 0, i32 %1906
%1908 = call i8* @strcpy(i8* %1907, i8* %1905) nounwind align 1
%1909 = call i32 @strlen(i8* getelementptr ([32 x i8]* @pgn_event, i32 0,i32 0))
%1910 = getelementptr [32 x i8]* @pgn_event, i32 0, i32 %1909
The last strlen is computable as 1908-@pgn_event, which means 1910=1908.
//===---------------------------------------------------------------------===//
186.crafty has this interesting pattern with the "out.4543" variable:
call void @llvm.memcpy.i32(