llvm-6502/test/Transforms/GVN/lpre-basic.ll

; RUN: opt < %s -gvn -enable-load-pre -S | grep {%PRE = phi}

define i32 @test(i32* %p, i1 %C) {
block1:
	br i1 %C, label %block2, label %block3

block2:
 br label %block4

block3:
  %b = bitcast i32 0 to i32
  store i32 %b, i32* %p
  br label %block4

block4:
  %PRE = load i32* %p
  ret i32 %PRE
}
Change tests from "opt %s" to "opt < %s" so that opt doesn't see the input filename so that opt doesn't print the input filename in the output so that grep lines in the tests don't unintentionally match strings in the input filename. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81537 91177308-0d34-0410-b5e6-96231b3b80d8 2009-09-11 18:01:28 +00:00			`; RUN: opt < %s -gvn -enable-load-pre -S \| grep {%PRE = phi}`
Implement PRE of loads in the GVN pass with a pretty cheap and straight-forward implementation. This does not require any extra alias analysis queries beyond what we already do for non-local loads. Some programs really really like load PRE. For example, SPASS triggers this ~1000 times, ~300 times in 255.vortex, and ~1500 times on 403.gcc. The biggest limitation to the implementation is that it does not split critical edges. This is a huge killer on many programs and should be addressed after the initial patch is enabled by default. The implementation of this should incidentally speed up rejection of non-local loads because it avoids creating the repl densemap in cases when it won't be used for fully redundant loads. This is currently disabled by default. Before I turn this on, I need to fix a couple of miscompilations in the testsuite, look at compile time performance numbers, and look at perf impact. This is pretty close to ready though. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60408 91177308-0d34-0410-b5e6-96231b3b80d8 2008-12-02 08:16:11 +00:00
			`define i32 @test(i32* %p, i1 %C) {`
			`block1:`
			`br i1 %C, label %block2, label %block3`

			`block2:`
			`br label %block4`

			`block3:`
			`%b = bitcast i32 0 to i32`
			`store i32 %b, i32* %p`
			`br label %block4`

			`block4:`
			`%PRE = load i32* %p`
			`ret i32 %PRE`
			`}`