mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-07-23 16:30:00 +00:00
d594ba0815
Make sure if we're truncating a constant that would then be sign extended that the sign extension of the truncated constant is the same as the original constant. > Canonicalize min/max expressions correctly. > > This patch introduces a canonical form for min/max idioms where one operand > is extended or truncated. This often happens when the other operand is a > constant. For example: > > %1 = icmp slt i32 %a, i32 0 > %2 = sext i32 %a to i64 > %3 = select i1 %1, i64 %2, i64 0 > > Would now be canonicalized into: > > %1 = icmp slt i32 %a, i32 0 > %2 = select i1 %1, i32 %a, i32 0 > %3 = sext i32 %2 to i64 > > This builds upon a patch posted by David Majenemer > (https://www.marc.info/?l=llvm-commits&m=143008038714141&w=2). That pass > passively stopped instcombine from ruining canonical patterns. This > patch additionally actively makes instcombine canonicalize too. > > Canonicalization of expressions involving a change in type from int->fp > or fp->int are not yet implemented. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237821 91177308-0d34-0410-b5e6-96231b3b80d8
113 lines
2.5 KiB
LLVM
113 lines
2.5 KiB
LLVM
; RUN: opt -S -instcombine < %s | FileCheck %s
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; CHECK-LABEL: @t1
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; CHECK-NEXT: icmp
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; CHECK-NEXT: select
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; CHECK-NEXT: sext
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define i64 @t1(i32 %a) {
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; This is the canonical form for a type-changing min/max.
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%1 = icmp slt i32 %a, 5
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%2 = select i1 %1, i32 %a, i32 5
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%3 = sext i32 %2 to i64
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ret i64 %3
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}
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; CHECK-LABEL: @t2
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; CHECK-NEXT: icmp
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; CHECK-NEXT: select
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; CHECK-NEXT: sext
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define i64 @t2(i32 %a) {
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; Check this is converted into canonical form, as above.
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%1 = icmp slt i32 %a, 5
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%2 = sext i32 %a to i64
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%3 = select i1 %1, i64 %2, i64 5
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ret i64 %3
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}
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; CHECK-LABEL: @t3
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; CHECK-NEXT: icmp
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; CHECK-NEXT: select
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; CHECK-NEXT: zext
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define i64 @t3(i32 %a) {
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; Same as @t2, with flipped operands and zext instead of sext.
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%1 = icmp ult i32 %a, 5
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%2 = zext i32 %a to i64
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%3 = select i1 %1, i64 5, i64 %2
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ret i64 %3
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}
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; CHECK-LABEL: @t4
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; CHECK-NEXT: icmp
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; CHECK-NEXT: select
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; CHECK-NEXT: trunc
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define i32 @t4(i64 %a) {
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; Same again, with trunc.
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%1 = icmp slt i64 %a, 5
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%2 = trunc i64 %a to i32
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%3 = select i1 %1, i32 %2, i32 5
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ret i32 %3
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}
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; CHECK-LABEL: @t5
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; CHECK-NEXT: icmp
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; CHECK-NEXT: zext
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; CHECK-NEXT: select
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define i64 @t5(i32 %a) {
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; Same as @t3, but with mismatched signedness between icmp and zext.
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; InstCombine should leave this alone.
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%1 = icmp slt i32 %a, 5
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%2 = zext i32 %a to i64
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%3 = select i1 %1, i64 5, i64 %2
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ret i64 %3
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}
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; CHECK-LABEL: @t6
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; CHECK-NEXT: icmp
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; CHECK-NEXT: select
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; CHECK-NEXT: sitofp
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define float @t6(i32 %a) {
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%1 = icmp slt i32 %a, 0
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%2 = select i1 %1, i32 %a, i32 0
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%3 = sitofp i32 %2 to float
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ret float %3
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}
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; CHECK-LABEL: @t7
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; CHECK-NEXT: icmp
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; CHECK-NEXT: select
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; CHECK-NEXT: trunc
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define i16 @t7(i32 %a) {
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%1 = icmp slt i32 %a, -32768
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%2 = trunc i32 %a to i16
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%3 = select i1 %1, i16 %2, i16 -32768
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ret i16 %3
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}
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; Just check for no infinite loop. InstSimplify liked to
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; "simplify" -32767 by removing all the sign bits,
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; which led to a canonicalization fight between different
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; parts of instcombine.
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define i32 @t8(i64 %a, i32 %b) {
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%1 = icmp slt i64 %a, -32767
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%2 = select i1 %1, i64 %a, i64 -32767
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%3 = trunc i64 %2 to i32
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%4 = icmp slt i32 %b, 42
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%5 = select i1 %4, i32 42, i32 %3
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%6 = icmp ne i32 %5, %b
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%7 = zext i1 %6 to i32
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ret i32 %7
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}
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; Ensure this doesn't get converted to a min/max.
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; CHECK-LABEL: @t9
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; CHECK-NEXT: icmp
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; CHECK-NEXT: sext
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; CHECK-NEXT: 4294967295
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; CHECK-NEXT: ret
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define i64 @t9(i32 %a) {
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%1 = icmp sgt i32 %a, -1
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%2 = sext i32 %a to i64
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%3 = select i1 %1, i64 %2, i64 4294967295
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ret i64 %3
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}
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