llvm-6502/test/Transforms/InstCombine/icmp.ll
Chris Lattner 3bf6815556 enhance x-(-A) -> x+A to preserve NUW/NSW.
Use the presence of NSW/NUW to fold "icmp (x+cst), x" to a constant in
cases where it would otherwise be undefined behavior.

Surprisingly (to me at least), this triggers hundreds of the times in
a few benchmarks: lencode, ldecode, and 466.h264ref seem to *really*
like this.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91812 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-21 04:04:05 +00:00

115 lines
2.2 KiB
LLVM

; RUN: opt < %s -instcombine -S | FileCheck %s
define i32 @test1(i32 %X) {
entry:
icmp slt i32 %X, 0 ; <i1>:0 [#uses=1]
zext i1 %0 to i32 ; <i32>:1 [#uses=1]
ret i32 %1
; CHECK: @test1
; CHECK: lshr i32 %X, 31
; CHECK-NEXT: ret i32
}
define i32 @test2(i32 %X) {
entry:
icmp ult i32 %X, -2147483648 ; <i1>:0 [#uses=1]
zext i1 %0 to i32 ; <i32>:1 [#uses=1]
ret i32 %1
; CHECK: @test2
; CHECK: lshr i32 %X, 31
; CHECK-NEXT: xor i32
; CHECK-NEXT: ret i32
}
define i32 @test3(i32 %X) {
entry:
icmp slt i32 %X, 0 ; <i1>:0 [#uses=1]
sext i1 %0 to i32 ; <i32>:1 [#uses=1]
ret i32 %1
; CHECK: @test3
; CHECK: ashr i32 %X, 31
; CHECK-NEXT: ret i32
}
define i32 @test4(i32 %X) {
entry:
icmp ult i32 %X, -2147483648 ; <i1>:0 [#uses=1]
sext i1 %0 to i32 ; <i32>:1 [#uses=1]
ret i32 %1
; CHECK: @test4
; CHECK: ashr i32 %X, 31
; CHECK-NEXT: xor i32
; CHECK-NEXT: ret i32
}
; PR4837
define <2 x i1> @test5(<2 x i64> %x) {
entry:
%V = icmp eq <2 x i64> %x, undef
ret <2 x i1> %V
; CHECK: @test5
; CHECK: ret <2 x i1> undef
}
define i32 @test6(i32 %a, i32 %b) {
%c = icmp sle i32 %a, -1
%d = zext i1 %c to i32
%e = sub i32 0, %d
%f = and i32 %e, %b
ret i32 %f
; CHECK: @test6
; CHECK-NEXT: ashr i32 %a, 31
; CHECK-NEXT: %f = and i32 %e, %b
; CHECK-NEXT: ret i32 %f
}
define i1 @test7(i32 %x) {
entry:
%a = add i32 %x, -1
%b = icmp ult i32 %a, %x
ret i1 %b
; CHECK: @test7
; CHECK: %b = icmp ne i32 %x, 0
; CHECK: ret i1 %b
}
define i1 @test8(i32 %x){
entry:
%a = add i32 %x, -1
%b = icmp eq i32 %a, %x
ret i1 %b
; CHECK: @test8
; CHECK: ret i1 false
}
define i1 @test9(i32 %x) {
entry:
%a = add i32 %x, -2
%b = icmp ugt i32 %x, %a
ret i1 %b
; CHECK: @test9
; CHECK: icmp ugt i32 %x, 1
; CHECK: ret i1 %b
}
define i1 @test10(i32 %x){
entry:
%a = add i32 %x, -1
%b = icmp slt i32 %a, %x
ret i1 %b
; CHECK: @test10
; CHECK: %b = icmp ne i32 %x, -2147483648
; CHECK: ret i1 %b
}
define i1 @test11(i32 %x) {
%a = add nsw i32 %x, 8
%b = icmp slt i32 %x, %a
ret i1 %b
; CHECK: @test11
; CHECK: ret i1 true
}