| ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py |
| ; RUN: opt < %s -O1 -S -mattr=+lzcnt | FileCheck %s |
| |
| target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128" |
| target triple = "x86_64-unknown-linux-gnu" |
| |
| ; This test ensures we are able to optimize the following loop to an llvm.abs |
| ; followed by an llvm.ctlz. |
| ; FIXME: LoopIdiom recongize is not forming llvm.ctlz. |
| |
| ; int ctlz_zero_check(int n) |
| ; { |
| ; n = n >= 0 ? n : -n; |
| ; int i = 0; |
| ; while(n) { |
| ; n >>= 1; |
| ; i++; |
| ; } |
| ; return i; |
| ; } |
| |
| define i32 @ctlz_loop_with_abs(i32 %n) { |
| ; CHECK-LABEL: @ctlz_loop_with_abs( |
| ; CHECK-NEXT: entry: |
| ; CHECK-NEXT: [[TOBOOL_NOT1:%.*]] = icmp eq i32 [[N:%.*]], 0 |
| ; CHECK-NEXT: br i1 [[TOBOOL_NOT1]], label [[WHILE_END:%.*]], label [[WHILE_BODY_PREHEADER:%.*]] |
| ; CHECK: while.body.preheader: |
| ; CHECK-NEXT: [[TMP0:%.*]] = call i32 @llvm.abs.i32(i32 [[N]], i1 true) |
| ; CHECK-NEXT: br label [[WHILE_BODY:%.*]] |
| ; CHECK: while.body: |
| ; CHECK-NEXT: [[N_ADDR_03:%.*]] = phi i32 [ [[TMP1:%.*]], [[WHILE_BODY]] ], [ [[TMP0]], [[WHILE_BODY_PREHEADER]] ] |
| ; CHECK-NEXT: [[I_02:%.*]] = phi i32 [ [[INC:%.*]], [[WHILE_BODY]] ], [ 0, [[WHILE_BODY_PREHEADER]] ] |
| ; CHECK-NEXT: [[TMP1]] = lshr i32 [[N_ADDR_03]], 1 |
| ; CHECK-NEXT: [[INC]] = add nuw nsw i32 [[I_02]], 1 |
| ; CHECK-NEXT: [[TOBOOL_NOT:%.*]] = icmp ult i32 [[N_ADDR_03]], 2 |
| ; CHECK-NEXT: br i1 [[TOBOOL_NOT]], label [[WHILE_END]], label [[WHILE_BODY]] |
| ; CHECK: while.end: |
| ; CHECK-NEXT: [[I_0_LCSSA:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[INC]], [[WHILE_BODY]] ] |
| ; CHECK-NEXT: ret i32 [[I_0_LCSSA]] |
| ; |
| entry: |
| %cmp = icmp sge i32 %n, 0 |
| br i1 %cmp, label %cond.true, label %cond.false |
| |
| cond.true: ; preds = %entry |
| br label %cond.end |
| |
| cond.false: ; preds = %entry |
| %sub = sub nsw i32 0, %n |
| br label %cond.end |
| |
| cond.end: ; preds = %cond.false, %cond.true |
| %cond = phi i32 [ %n, %cond.true ], [ %sub, %cond.false ] |
| br label %while.cond |
| |
| while.cond: ; preds = %while.body, %cond.end |
| %i.0 = phi i32 [ 0, %cond.end ], [ %inc, %while.body ] |
| %n.addr.0 = phi i32 [ %cond, %cond.end ], [ %shr, %while.body ] |
| %tobool = icmp ne i32 %n.addr.0, 0 |
| br i1 %tobool, label %while.body, label %while.end |
| |
| while.body: ; preds = %while.cond |
| %shr = ashr i32 %n.addr.0, 1 |
| %inc = add nsw i32 %i.0, 1 |
| br label %while.cond |
| |
| while.end: ; preds = %while.cond |
| ret i32 %i.0 |
| } |