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now that the cost model has changed, we can always consider

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elimination of a sign extend to be a win, which simplifies 
the client of CanEvaluateSExtd, and allows us to eliminate
more casts (examples taken from real code).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93109 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2010-01-10 07:40:50 +00:00
parent 24e64df7ec
commit dde5ee5d37
2 changed files with 60 additions and 27 deletions
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46
test/Transforms/InstCombine/cast.ll
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@@ -185,8 +185,8 @@ define i32 @test22(i32 %X) {
%c2 = sext i8 %c1 to i32 ; <i32> [#uses=1]
%RV = shl i32 %c2, 24 ; <i32> [#uses=1]
ret i32 %RV
; CHECK: %RV = shl i32 %X, 24
; CHECK: ret i32 %RV
; CHECK: shl i32 %X, 24
; CHECK-NEXT: ret i32
}
define i32 @test23(i32 %X) {
@@ -457,3 +457,45 @@ define i64 @test48(i8 %A, i8 %a) {
; CHECK-NEXT: ret i64 %D
}
define i64 @test49(i64 %A) {
%B = trunc i64 %A to i32
%C = or i32 %B, 1
%D = sext i32 %C to i64
ret i64 %D
; CHECK: @test49
; CHECK-NEXT: %C = shl i64 %A, 32
; CHECK-NEXT: ashr i64 %C, 32
; CHECK-NEXT: %D = or i64 {{.*}}, 1
; CHECK-NEXT: ret i64 %D
}
define i64 @test50(i64 %A) {
%a = lshr i64 %A, 2
%B = trunc i64 %a to i32
%D = add i32 %B, -1
%E = sext i32 %D to i64
ret i64 %E
; CHECK: @test50
; CHECK-NEXT: shl i64 %A, 30
; CHECK-NEXT: add i64 {{.*}}, -4294967296
; CHECK-NEXT: %E = ashr i64 {{.*}}, 32
; CHECK-NEXT: ret i64 %E
}
define i64 @test51(i64 %A, i1 %cond) {
%B = trunc i64 %A to i32
%C = and i32 %B, -2
%D = or i32 %B, 1
%E = select i1 %cond, i32 %C, i32 %D
%F = sext i32 %E to i64
ret i64 %F
; CHECK: @test51
; CHECK-NEXT: %C = and i64 %A, 4294967294
; CHECK-NEXT: %D = or i64 %A, 1
; CHECK-NEXT: %E = select i1 %cond, i64 %C, i64 %D
; CHECK-NEXT: %sext = shl i64 %E, 32
; CHECK-NEXT: %F = ashr i64 %sext, 32
; CHECK-NEXT: ret i64 %F
}