llvm/test/Transforms/InstCombine/ffs-1.ll
Jingyue Wu dcc9291851 [InstCombine] mark ADD with nuw if no unsigned overflow
Summary:
As a starting step, we only use one simple heuristic: if the sign bits
of both a and b are zero, we can prove "add a, b" do not unsigned
overflow, and thus convert it to "add nuw a, b".

Updated all affected tests and added two new tests (@zero_sign_bit and
@zero_sign_bit2) in AddOverflow.ll

Test Plan: make check-all

Reviewers: eliben, rafael, meheff, chandlerc

Reviewed By: chandlerc

Subscribers: chandlerc, llvm-commits

Differential Revision: http://reviews.llvm.org/D4144

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211084 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-17 00:42:07 +00:00

135 lines
3.7 KiB
LLVM

; Test that the ffs* library call simplifier works correctly.
;
; RUN: opt < %s -instcombine -S | FileCheck %s
; RUN: opt < %s -mtriple i386-pc-linux -instcombine -S | FileCheck %s -check-prefix=CHECK-LINUX
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
declare i32 @ffs(i32)
declare i32 @ffsl(i32)
declare i32 @ffsll(i64)
; Check ffs(0) -> 0.
define i32 @test_simplify1() {
; CHECK-LABEL: @test_simplify1(
%ret = call i32 @ffs(i32 0)
ret i32 %ret
; CHECK-NEXT: ret i32 0
}
define i32 @test_simplify2() {
; CHECK-LINUX-LABEL: @test_simplify2(
%ret = call i32 @ffsl(i32 0)
ret i32 %ret
; CHECK-LINUX-NEXT: ret i32 0
}
define i32 @test_simplify3() {
; CHECK-LINUX-LABEL: @test_simplify3(
%ret = call i32 @ffsll(i64 0)
ret i32 %ret
; CHECK-LINUX-NEXT: ret i32 0
}
; Check ffs(c) -> cttz(c) + 1, where 'c' is a constant.
define i32 @test_simplify4() {
; CHECK-LABEL: @test_simplify4(
%ret = call i32 @ffs(i32 1)
ret i32 %ret
; CHECK-NEXT: ret i32 1
}
define i32 @test_simplify5() {
; CHECK-LABEL: @test_simplify5(
%ret = call i32 @ffs(i32 2048)
ret i32 %ret
; CHECK-NEXT: ret i32 12
}
define i32 @test_simplify6() {
; CHECK-LABEL: @test_simplify6(
%ret = call i32 @ffs(i32 65536)
ret i32 %ret
; CHECK-NEXT: ret i32 17
}
define i32 @test_simplify7() {
; CHECK-LINUX-LABEL: @test_simplify7(
%ret = call i32 @ffsl(i32 65536)
ret i32 %ret
; CHECK-LINUX-NEXT: ret i32 17
}
define i32 @test_simplify8() {
; CHECK-LINUX-LABEL: @test_simplify8(
%ret = call i32 @ffsll(i64 1024)
ret i32 %ret
; CHECK-LINUX-NEXT: ret i32 11
}
define i32 @test_simplify9() {
; CHECK-LINUX-LABEL: @test_simplify9(
%ret = call i32 @ffsll(i64 65536)
ret i32 %ret
; CHECK-LINUX-NEXT: ret i32 17
}
define i32 @test_simplify10() {
; CHECK-LINUX-LABEL: @test_simplify10(
%ret = call i32 @ffsll(i64 17179869184)
ret i32 %ret
; CHECK-LINUX-NEXT: ret i32 35
}
define i32 @test_simplify11() {
; CHECK-LINUX-LABEL: @test_simplify11(
%ret = call i32 @ffsll(i64 281474976710656)
ret i32 %ret
; CHECK-LINUX-NEXT: ret i32 49
}
define i32 @test_simplify12() {
; CHECK-LINUX-LABEL: @test_simplify12(
%ret = call i32 @ffsll(i64 1152921504606846976)
ret i32 %ret
; CHECK-LINUX-NEXT: ret i32 61
}
; Check ffs(x) -> x != 0 ? (i32)llvm.cttz(x) + 1 : 0.
define i32 @test_simplify13(i32 %x) {
; CHECK-LABEL: @test_simplify13(
%ret = call i32 @ffs(i32 %x)
; CHECK-NEXT: [[CTTZ:%[a-z0-9]+]] = call i32 @llvm.cttz.i32(i32 %x, i1 false)
; CHECK-NEXT: [[INC:%[a-z0-9]+]] = add nuw nsw i32 [[CTTZ]], 1
; CHECK-NEXT: [[CMP:%[a-z0-9]+]] = icmp ne i32 %x, 0
; CHECK-NEXT: [[RET:%[a-z0-9]+]] = select i1 [[CMP]], i32 [[INC]], i32 0
ret i32 %ret
; CHECK-NEXT: ret i32 [[RET]]
}
define i32 @test_simplify14(i32 %x) {
; CHECK-LINUX-LABEL: @test_simplify14(
%ret = call i32 @ffsl(i32 %x)
; CHECK-LINUX-NEXT: [[CTTZ:%[a-z0-9]+]] = call i32 @llvm.cttz.i32(i32 %x, i1 false)
; CHECK-LINUX-NEXT: [[INC:%[a-z0-9]+]] = add nuw nsw i32 [[CTTZ]], 1
; CHECK-LINUX-NEXT: [[CMP:%[a-z0-9]+]] = icmp ne i32 %x, 0
; CHECK-LINUX-NEXT: [[RET:%[a-z0-9]+]] = select i1 [[CMP]], i32 [[INC]], i32 0
ret i32 %ret
; CHECK-LINUX-NEXT: ret i32 [[RET]]
}
define i32 @test_simplify15(i64 %x) {
; CHECK-LINUX-LABEL: @test_simplify15(
%ret = call i32 @ffsll(i64 %x)
; CHECK-LINUX-NEXT: [[CTTZ:%[a-z0-9]+]] = call i64 @llvm.cttz.i64(i64 %x, i1 false)
; CHECK-LINUX-NEXT: [[INC:%[a-z0-9]+]] = add nuw nsw i64 [[CTTZ]], 1
; CHECK-LINUX-NEXT: [[TRUNC:%[a-z0-9]+]] = trunc i64 [[INC]] to i32
; CHECK-LINUX-NEXT: [[CMP:%[a-z0-9]+]] = icmp ne i64 %x, 0
; CHECK-LINUX-NEXT: [[RET:%[a-z0-9]+]] = select i1 [[CMP]], i32 [[TRUNC]], i32 0
ret i32 %ret
; CHECK-LINUX-NEXT: ret i32 [[RET]]
}