llvm-6502/test/Transforms/IndVarSimplify/iv-zext.ll
Andrew Trick 2fabd464ae indvars -disable-iv-rewrite: Adds support for eliminating identity
ops.

This is a rewrite of the IV simplification algorithm used by
-disable-iv-rewrite. To avoid perturbing the default mode, I
temporarily split the driver and created SimplifyIVUsersNoRewrite. The
idea is to avoid doing opcode/pattern matching inside
IndVarSimplify. SCEV already does it. We want to optimize with the
full generality of SCEV, but optimize def-use chains top down on-demand rather
than rewriting the entire expression bottom-up. This was easy to do
for operations that SCEV can prove are identity function. So we're now
eliminating bitmasks and zero extends this way.

A result of this rewrite is that indvars -disable-iv-rewrite no longer
requires IVUsers.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133502 91177308-0d34-0410-b5e6-96231b3b80d8
2011-06-21 03:22:38 +00:00

35 lines
931 B
LLVM

; RUN: opt < %s -indvars -S | FileCheck %s
; RUN: opt < %s -indvars -disable-iv-rewrite -S | FileCheck %s
; CHECK-NOT: and
; CHECK-NOT: zext
target datalayout = "-p:64:64:64-n:32:64"
define void @foo(double* %d, i64 %n) nounwind {
entry:
br label %loop
loop:
%indvar = phi i64 [ 0, %entry ], [ %indvar.next, %loop ]
%indvar.i8 = and i64 %indvar, 255
%t0 = getelementptr double* %d, i64 %indvar.i8
%t1 = load double* %t0
%t2 = fmul double %t1, 0.1
store double %t2, double* %t0
%indvar.i24 = and i64 %indvar, 16777215
%t3 = getelementptr double* %d, i64 %indvar.i24
%t4 = load double* %t3
%t5 = fmul double %t4, 2.3
store double %t5, double* %t3
%t6 = getelementptr double* %d, i64 %indvar
%t7 = load double* %t6
%t8 = fmul double %t7, 4.5
store double %t8, double* %t6
%indvar.next = add i64 %indvar, 1
%exitcond = icmp eq i64 %indvar.next, 10
br i1 %exitcond, label %return, label %loop
return:
ret void
}