From 2dae65d13b958c42561ece77e7f344ffb00c26c7 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Wed, 10 Dec 2008 01:30:48 +0000 Subject: [PATCH] move an entry, add some notes, remove a completed item (IMPLICIT_DEF) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60821 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/README.txt | 75 ++++++++++++++++++++++--------------------- 1 file changed, 38 insertions(+), 37 deletions(-) diff --git a/lib/Target/README.txt b/lib/Target/README.txt index 646961efe18..e0cab2af49c 100644 --- a/lib/Target/README.txt +++ b/lib/Target/README.txt @@ -2,13 +2,6 @@ Target Independent Opportunities: //===---------------------------------------------------------------------===// -We should make the various target's "IMPLICIT_DEF" instructions be a single -target-independent opcode like TargetInstrInfo::INLINEASM. This would allow -us to eliminate the TargetInstrDesc::isImplicitDef() method, and would allow -us to avoid having to define this for every target for every register class. - -//===---------------------------------------------------------------------===// - With the recent changes to make the implicit def/use set explicit in machineinstrs, we should change the target descriptions for 'call' instructions so that the .td files don't list all the call-clobbered registers as implicit @@ -30,7 +23,10 @@ Make the PPC branch selector target independant //===---------------------------------------------------------------------===// Get the C front-end to expand hypot(x,y) -> llvm.sqrt(x*x+y*y) when errno and -precision don't matter (ffastmath). Misc/mandel will like this. :) +precision don't matter (ffastmath). Misc/mandel will like this. :) This isn't +safe in general, even on darwin. See the libm implementation of hypot for +examples (which special case when x/y are exactly zero to get signed zeros etc +right). //===---------------------------------------------------------------------===// @@ -166,6 +162,9 @@ Expand these to calls of sin/cos and stores: Doing so could allow SROA of the destination pointers. See also: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17687 +This is now easily doable with MRVs. We could even make an intrinsic for this +if anyone cared enough about sincos. + //===---------------------------------------------------------------------===// Scalar Repl cannot currently promote this testcase to 'ret long cst': @@ -511,6 +510,8 @@ int i; } } +BasicAA also doesn't do this for add. It needs to know that &A[i+1] != &A[i]. + //===---------------------------------------------------------------------===// We should investigate an instruction sinking pass. Consider this silly @@ -925,35 +926,6 @@ vec2d foo () { //===---------------------------------------------------------------------===// -This C++ file: -void g(); struct A { int n; int m; A& operator++(void) { ++n; if (n == m) g(); -return *this; } A() : n(0), m(0) { } friend bool operator!=(A const& a1, -A const& a2) { return a1.n != a2.n; } }; void testfunction(A& iter) { A const -end; while (iter != end) ++iter; } - -Compiles down to: - -bb: ; preds = %bb3.backedge, %bb.nph - %.rle = phi i32 [ %1, %bb.nph ], [ %7, %bb3.backedge ] ; [#uses=1] - %4 = add i32 %.rle, 1 ; [#uses=2] - store i32 %4, i32* %0, align 4 - %5 = load i32* %3, align 4 ; [#uses=1] - %6 = icmp eq i32 %4, %5 ; [#uses=1] - br i1 %6, label %bb1, label %bb3.backedge - -bb1: ; preds = %bb - tail call void @_Z1gv() - br label %bb3.backedge - -bb3.backedge: ; preds = %bb, %bb1 - %7 = load i32* %0, align 4 ; [#uses=2] - - -The %7 load is partially redundant with the store of %4 to %0, GVN's PRE -should remove it, but it doesn't apply to memory objects. - -//===---------------------------------------------------------------------===// - Better mod/ref analysis for scanf would allow us to eliminate the vtable and a bunch of other stuff from this example (see PR1604): @@ -1432,3 +1404,32 @@ void foo (int a, struct T b) //===---------------------------------------------------------------------===// +This C++ file: +void g(); struct A { int n; int m; A& operator++(void) { ++n; if (n == m) g(); +return *this; } A() : n(0), m(0) { } friend bool operator!=(A const& a1, +A const& a2) { return a1.n != a2.n; } }; void testfunction(A& iter) { A const +end; while (iter != end) ++iter; } + +Compiles down to: + +bb: ; preds = %bb3.backedge, %bb.nph + %.rle = phi i32 [ %1, %bb.nph ], [ %7, %bb3.backedge ] ; [#uses=1] + %4 = add i32 %.rle, 1 ; [#uses=2] + store i32 %4, i32* %0, align 4 + %5 = load i32* %3, align 4 ; [#uses=1] + %6 = icmp eq i32 %4, %5 ; [#uses=1] + br i1 %6, label %bb1, label %bb3.backedge + +bb1: ; preds = %bb + tail call void @_Z1gv() + br label %bb3.backedge + +bb3.backedge: ; preds = %bb, %bb1 + %7 = load i32* %0, align 4 ; [#uses=2] + + +The %7 load is partially redundant with the store of %4 to %0, GVN's PRE +should remove it, but it doesn't apply to memory objects. + +//===---------------------------------------------------------------------===// +