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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26513 91177308-0d34-0410-b5e6-96231b3b80d8
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Chris Lattner 2006-03-04 01:19:34 +00:00
parent 8df346b4e8
commit b27b69f283
1 changed files with 15 additions and 0 deletions
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15
lib/Target/README.txt
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@ -86,3 +86,18 @@ int f(int a, int b){ return a * a + 2 * a * b + b * b; }
into:
int f(int a, int b) { return a * (a + 2 * b) + b * b; }
to eliminate a multiply.
//===---------------------------------------------------------------------===//
On targets with expensive 64-bit multiply, we could LSR this:
for (i = ...; ++i) {
x = 1ULL << i;
into:
long long tmp = 1;
for (i = ...; ++i, tmp+=tmp)
x = tmp;
This would be a win on ppc32, but not x86 or ppc64.