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llvm-mirror/test/Transforms/SimplifyCFG/sink-common-code.ll
James Molloy d99f6d6d8b [SimplifyCFG] Rewrite SinkThenElseCodeToEnd
The new version has several advantages:
  1) IMSHO it's more readable and neater
  2) It handles loads and stores properly
  3) It can handle any number of incoming blocks rather than just two. I'll be taking advantage of this in a followup patch.

With this change we can now finally sink load-modify-store idioms such as:

    if (a)
      return *b += 3;
    else
      return *b += 4;

    =>

    %z = load i32, i32* %y
    %.sink = select i1 %a, i32 5, i32 7
    %b = add i32 %z, %.sink
    store i32 %b, i32* %y
    ret i32 %b

When this works for switches it'll be even more powerful.

Round 4. This time we should handle all instructions correctly, and not replace any operands that need to be constant with variables.

This was really hard to determine safely, so the helper function should be put into the Instruction API. I'll do that as a followup.

llvm-svn: 279443
2016-08-22 17:40:23 +00:00

313 lines
6.3 KiB
LLVM

; RUN: opt < %s -simplifycfg -S | FileCheck %s
define zeroext i1 @test1(i1 zeroext %flag, i32 %blksA, i32 %blksB, i32 %nblks) {
entry:
br i1 %flag, label %if.then, label %if.else
; CHECK-LABEL: test1
; CHECK: add
; CHECK: select
; CHECK: icmp
; CHECK-NOT: br
if.then:
%cmp = icmp uge i32 %blksA, %nblks
%frombool1 = zext i1 %cmp to i8
br label %if.end
if.else:
%add = add i32 %nblks, %blksB
%cmp2 = icmp ule i32 %add, %blksA
%frombool3 = zext i1 %cmp2 to i8
br label %if.end
if.end:
%obeys.0 = phi i8 [ %frombool1, %if.then ], [ %frombool3, %if.else ]
%tobool4 = icmp ne i8 %obeys.0, 0
ret i1 %tobool4
}
define zeroext i1 @test2(i1 zeroext %flag, i32 %blksA, i32 %blksB, i32 %nblks) {
entry:
br i1 %flag, label %if.then, label %if.else
; CHECK-LABEL: test2
; CHECK: add
; CHECK: select
; CHECK: icmp
; CHECK-NOT: br
if.then:
%cmp = icmp uge i32 %blksA, %nblks
%frombool1 = zext i1 %cmp to i8
br label %if.end
if.else:
%add = add i32 %nblks, %blksB
%cmp2 = icmp uge i32 %blksA, %add
%frombool3 = zext i1 %cmp2 to i8
br label %if.end
if.end:
%obeys.0 = phi i8 [ %frombool1, %if.then ], [ %frombool3, %if.else ]
%tobool4 = icmp ne i8 %obeys.0, 0
ret i1 %tobool4
}
declare i32 @foo(i32, i32) nounwind readnone
define i32 @test3(i1 zeroext %flag, i32 %x, i32 %y) {
entry:
br i1 %flag, label %if.then, label %if.else
if.then:
%x0 = call i32 @foo(i32 %x, i32 0) nounwind readnone
%y0 = call i32 @foo(i32 %x, i32 1) nounwind readnone
br label %if.end
if.else:
%x1 = call i32 @foo(i32 %y, i32 0) nounwind readnone
%y1 = call i32 @foo(i32 %y, i32 1) nounwind readnone
br label %if.end
if.end:
%xx = phi i32 [ %x0, %if.then ], [ %x1, %if.else ]
%yy = phi i32 [ %y0, %if.then ], [ %y1, %if.else ]
%ret = add i32 %xx, %yy
ret i32 %ret
}
; CHECK-LABEL: test3
; CHECK: select
; CHECK: call
; CHECK: call
; CHECK: add
; CHECK-NOT: br
define i32 @test4(i1 zeroext %flag, i32 %x, i32* %y) {
entry:
br i1 %flag, label %if.then, label %if.else
if.then:
%a = add i32 %x, 5
store i32 %a, i32* %y
br label %if.end
if.else:
%b = add i32 %x, 7
store i32 %b, i32* %y
br label %if.end
if.end:
ret i32 1
}
; CHECK-LABEL: test4
; CHECK: select
; CHECK: store
; CHECK-NOT: store
define i32 @test5(i1 zeroext %flag, i32 %x, i32* %y) {
entry:
br i1 %flag, label %if.then, label %if.else
if.then:
%a = add i32 %x, 5
store volatile i32 %a, i32* %y
br label %if.end
if.else:
%b = add i32 %x, 7
store i32 %b, i32* %y
br label %if.end
if.end:
ret i32 1
}
; CHECK-LABEL: test5
; CHECK: store volatile
; CHECK: store
define i32 @test6(i1 zeroext %flag, i32 %x, i32* %y) {
entry:
br i1 %flag, label %if.then, label %if.else
if.then:
%a = add i32 %x, 5
store volatile i32 %a, i32* %y
br label %if.end
if.else:
%b = add i32 %x, 7
store volatile i32 %b, i32* %y
br label %if.end
if.end:
ret i32 1
}
; CHECK-LABEL: test6
; CHECK: select
; CHECK: store volatile
; CHECK-NOT: store
define i32 @test7(i1 zeroext %flag, i32 %x, i32* %y) {
entry:
br i1 %flag, label %if.then, label %if.else
if.then:
%z = load volatile i32, i32* %y
%a = add i32 %z, 5
store volatile i32 %a, i32* %y
br label %if.end
if.else:
%w = load volatile i32, i32* %y
%b = add i32 %w, 7
store volatile i32 %b, i32* %y
br label %if.end
if.end:
ret i32 1
}
; CHECK-LABEL: test7
; CHECK-DAG: select
; CHECK-DAG: load volatile
; CHECK: store volatile
; CHECK-NOT: load
; CHECK-NOT: store
; %z and %w are in different blocks. We shouldn't sink the add because
; there may be intervening memory instructions.
define i32 @test8(i1 zeroext %flag, i32 %x, i32* %y) {
entry:
%z = load volatile i32, i32* %y
br i1 %flag, label %if.then, label %if.else
if.then:
%a = add i32 %z, 5
store volatile i32 %a, i32* %y
br label %if.end
if.else:
%w = load volatile i32, i32* %y
%b = add i32 %w, 7
store volatile i32 %b, i32* %y
br label %if.end
if.end:
ret i32 1
}
; CHECK-LABEL: test8
; CHECK: add
; CHECK: add
; The extra store in %if.then means %z and %w are not equivalent.
define i32 @test9(i1 zeroext %flag, i32 %x, i32* %y, i32* %p) {
entry:
br i1 %flag, label %if.then, label %if.else
if.then:
store i32 7, i32* %p
%z = load volatile i32, i32* %y
store i32 6, i32* %p
%a = add i32 %z, 5
store volatile i32 %a, i32* %y
br label %if.end
if.else:
%w = load volatile i32, i32* %y
%b = add i32 %w, 7
store volatile i32 %b, i32* %y
br label %if.end
if.end:
ret i32 1
}
; CHECK-LABEL: test9
; CHECK: add
; CHECK: add
%struct.anon = type { i32, i32 }
; The GEP indexes a struct type so cannot have a variable last index.
define i32 @test10(i1 zeroext %flag, i32 %x, i32* %y, %struct.anon* %s) {
entry:
br i1 %flag, label %if.then, label %if.else
if.then:
%dummy = add i32 %x, 5
%gepa = getelementptr inbounds %struct.anon, %struct.anon* %s, i32 0, i32 0
store volatile i32 %x, i32* %gepa
br label %if.end
if.else:
%dummy1 = add i32 %x, 6
%gepb = getelementptr inbounds %struct.anon, %struct.anon* %s, i32 0, i32 1
store volatile i32 %x, i32* %gepb
br label %if.end
if.end:
ret i32 1
}
; CHECK-LABEL: test10
; CHECK: getelementptr
; CHECK: getelementptr
; CHECK: phi
; CHECK: store volatile
; The shufflevector's mask operand cannot be merged in a PHI.
define i32 @test11(i1 zeroext %flag, i32 %w, <2 x i32> %x, <2 x i32> %y) {
entry:
br i1 %flag, label %if.then, label %if.else
if.then:
%dummy = add i32 %w, 5
%sv1 = shufflevector <2 x i32> %x, <2 x i32> %y, <2 x i32> <i32 0, i32 1>
br label %if.end
if.else:
%dummy1 = add i32 %w, 6
%sv2 = shufflevector <2 x i32> %x, <2 x i32> %y, <2 x i32> <i32 1, i32 0>
br label %if.end
if.end:
%p = phi <2 x i32> [ %sv1, %if.then ], [ %sv2, %if.else ]
ret i32 1
}
; CHECK-LABEL: test11
; CHECK: shufflevector
; CHECK: shufflevector
; We can't common an intrinsic!
define i32 @test12(i1 zeroext %flag, i32 %w, i32 %x, i32 %y) {
entry:
br i1 %flag, label %if.then, label %if.else
if.then:
%dummy = add i32 %w, 5
%sv1 = call i32 @llvm.ctlz.i32(i32 %x)
br label %if.end
if.else:
%dummy1 = add i32 %w, 6
%sv2 = call i32 @llvm.cttz.i32(i32 %x)
br label %if.end
if.end:
%p = phi i32 [ %sv1, %if.then ], [ %sv2, %if.else ]
ret i32 1
}
declare i32 @llvm.ctlz.i32(i32 %x) readnone
declare i32 @llvm.cttz.i32(i32 %x) readnone
; CHECK-LABEL: test12
; CHECK: call i32 @llvm.ctlz
; CHECK: call i32 @llvm.cttz