9 Commits

Author	SHA1	Message	Date
Chris Lattner	9c69406f2b	fix a miscompilation of tramp3d-v4: when forming a memcpy, we have to make ... sure that the loop we're promoting into a memcpy doesn't mutate the input of the memcpy. Before we were just checking that the dest of the memcpy wasn't mod/ref'd by the loop. llvm-svn: 122712	2011-01-02 21:14:18 +00:00
Chris Lattner	5702a43c09	If a loop iterates exactly once (has backedge count = 0) then don't ... mess with it. We'd rather peel/unroll it than convert all of its stores into memsets. llvm-svn: 122711	2011-01-02 20:24:21 +00:00
Chris Lattner	8455b6e45e	enhance loop idiom recognition to scan *all* unconditionally executed ... blocks in a loop, instead of just the header block. This makes it more aggressive, able to handle Duncan's Ada examples. llvm-svn: 122704	2011-01-02 19:01:03 +00:00
Chris Lattner	ddf58010bd	Allow loop-idiom to run on multiple BB loops, but still only scan the loop ... header for now for memset/memcpy opportunities. It turns out that loop-rotate is successfully rotating loops, but *DOESN'T MERGE THE BLOCKS*, turning "for loops" into 2 basic block loops that loop-idiom was ignoring. With this fix, we form many *many* more memcpy and memsets than before, including on the "history" loops in the viterbi benchmark, which look like this: for (j=0; j<MAX_history; ++j) { history_new[i][j+1] = history[2*i][j]; } Transforming these loops into memcpy's speeds up the viterbi benchmark from 11.98s to 3.55s on my machine. Woo. llvm-svn: 122685	2011-01-02 07:58:36 +00:00
Chris Lattner	85b6d81d41	teach loop idiom recognition to form memcpy's from simple loops. ... llvm-svn: 122678	2011-01-02 03:37:56 +00:00
Chris Lattner	a3514441e0	add a validity check that was missed, fixing a crash on the ... new testcase. llvm-svn: 122662	2011-01-01 20:12:04 +00:00
Chris Lattner	91a4435875	improve validity check to handle constant-trip-count loops more ... aggressively. In practice, this doesn't help anything though, see the todo. llvm-svn: 122660	2011-01-01 19:54:22 +00:00
Chris Lattner	8b3baf6d75	implement the "no aliasing accesses in loop" safety check. This pass ... should be correct now. llvm-svn: 122659	2011-01-01 19:39:01 +00:00
Chris Lattner	29e14edc8d	implement enough of the memset inference algorithm to recognize and insert ... memsets. This is still missing one important validity check, but this is enough to compile stuff like this: void test0(std::vector<char> &X) { for (std::vector<char>::iterator I = X.begin(), E = X.end(); I != E; ++I) *I = 0; } void test1(std::vector<int> &X) { for (long i = 0, e = X.size(); i != e; ++i) X[i] = 0x01010101; } With: $ clang t.cpp -S -o - -O2 -emit-llvm | opt -loop-idiom | opt -O3 | llc to: __Z5test0RSt6vectorIcSaIcEE: ## @_Z5test0RSt6vectorIcSaIcEE ## BB#0: ## %entry subq $8, %rsp movq (%rdi), %rax movq 8(%rdi), %rsi cmpq %rsi, %rax je LBB0_2 ## BB#1: ## %bb.nph subq %rax, %rsi movq %rax, %rdi callq ___bzero LBB0_2: ## %for.end addq $8, %rsp ret ... __Z5test1RSt6vectorIiSaIiEE: ## @_Z5test1RSt6vectorIiSaIiEE ## BB#0: ## %entry subq $8, %rsp movq (%rdi), %rax movq 8(%rdi), %rdx subq %rax, %rdx cmpq $4, %rdx jb LBB1_2 ## BB#1: ## %for.body.preheader andq $-4, %rdx movl $1, %esi movq %rax, %rdi callq _memset LBB1_2: ## %for.end addq $8, %rsp ret llvm-svn: 122573	2010-12-26 23:42:51 +00:00