From c92da3882ee4e18153bb36fcdf33af393aba8259 Mon Sep 17 00:00:00 2001 From: Evan Cheng Date: Sat, 3 Nov 2007 07:20:12 +0000 Subject: There are times when the coalescer would not coalesce away a copy but the copy can be eliminated by the allocator is the destination and source targets the same register. The most common case is when the source and destination registers are in different class. For example, on x86 mov32to32_ targets GR32_ which contains a subset of the registers in GR32. The allocator can do 2 things: 1. Set the preferred allocation for the destination of a copy to that of its source. 2. After allocation is done, change the allocation of a copy destination (if legal) so the copy can be eliminated. This eliminates 443 extra moves from 403.gcc. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43662 91177308-0d34-0410-b5e6-96231b3b80d8 --- test/CodeGen/X86/postalloc-coalescing.ll | 35 ++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 test/CodeGen/X86/postalloc-coalescing.ll (limited to 'test/CodeGen/X86/postalloc-coalescing.ll') diff --git a/test/CodeGen/X86/postalloc-coalescing.ll b/test/CodeGen/X86/postalloc-coalescing.ll new file mode 100644 index 0000000..9c44a5a --- /dev/null +++ b/test/CodeGen/X86/postalloc-coalescing.ll @@ -0,0 +1,35 @@ +; RUN: llvm-as < %s | llc -march=x86 | grep mov | count 3 + +define fastcc i32 @_Z18yy_get_next_bufferv() { +entry: + br label %bb131 + +bb116: ; preds = %bb131 + %tmp125126 = trunc i32 %c.1 to i8 ; [#uses=1] + store i8 %tmp125126, i8* null, align 1 + br label %bb131 + +bb131: ; preds = %bb116, %entry + %c.2 = phi i32 [ %c.1, %bb116 ], [ 42, %entry ] ; [#uses=1] + %c.1 = select i1 false, i32 0, i32 %c.2 ; [#uses=4] + %tmp181 = icmp eq i32 %c.1, -1 ; [#uses=1] + br i1 %tmp181, label %bb158, label %bb116 + +bb158: ; preds = %bb131 + br i1 true, label %cond_true163, label %cond_next178 + +cond_true163: ; preds = %bb158 + %tmp172173 = trunc i32 %c.1 to i8 ; [#uses=1] + store i8 %tmp172173, i8* null, align 1 + br label %cond_next178 + +cond_next178: ; preds = %cond_true163, %bb158 + %tmp180 = icmp eq i32 %c.1, -1 ; [#uses=1] + br i1 %tmp180, label %cond_next184, label %cond_next199 + +cond_next184: ; preds = %cond_next178 + ret i32 0 + +cond_next199: ; preds = %cond_next178 + ret i32 0 +} -- cgit v1.1