mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2024-11-24 03:33:20 +01:00
49b37e626b
This is a re-application of a r303497 that was reverted in r303498. I thought it had broken a bot when it had not (the breakage did not go away with the revert). This change makes the split between the "exact" backedge taken count and the "maximum" backedge taken count a bit more obvious. Both of these are upper bounds on the number of times the loop header executes (since SCEV does not account for most kinds of abnormal control flow), but the latter is guaranteed to be a constant. There were a few places where the max backedge taken count *was* a non-constant; I've changed those to compute constants instead. At this point, I'm not sure if the constant max backedge count can be computed by calling `getUnsignedRange(Exact).getUnsignedMax()` without losing precision. If it can, we can simplify even further by making `getMaxBackedgeTakenCount` a thin wrapper around `getBackedgeTakenCount` and `getUnsignedRange`. llvm-svn: 303531
88 lines
2.0 KiB
LLVM
88 lines
2.0 KiB
LLVM
; RUN: opt < %s -scalar-evolution -analyze | FileCheck %s
|
|
|
|
define void @test1(i32 %n) {
|
|
entry:
|
|
%s = mul i32 %n, 96
|
|
br label %loop
|
|
loop:
|
|
%i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
|
|
%i.next = add i32 %i, 32
|
|
%t = icmp ne i32 %i.next, %s
|
|
br i1 %t, label %loop, label %exit
|
|
exit:
|
|
ret void
|
|
|
|
; CHECK-LABEL: @test1
|
|
; CHECK: Loop %loop: backedge-taken count is ((-32 + (96 * %n)) /u 32)
|
|
; CHECK: Loop %loop: max backedge-taken count is 134217727
|
|
}
|
|
|
|
; PR19183
|
|
define i32 @test2(i32 %n) {
|
|
entry:
|
|
%s = and i32 %n, -32
|
|
br label %loop
|
|
loop:
|
|
%i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
|
|
%i.next = add i32 %i, 32
|
|
%t = icmp ne i32 %i.next, %s
|
|
br i1 %t, label %loop, label %exit
|
|
exit:
|
|
ret i32 %i
|
|
|
|
; CHECK-LABEL: @test2
|
|
; CHECK: Loop %loop: backedge-taken count is ((-32 + (32 * (%n /u 32))) /u 32)
|
|
; CHECK: Loop %loop: max backedge-taken count is 134217727
|
|
}
|
|
|
|
define void @test3(i32 %n) {
|
|
entry:
|
|
%s = mul i32 %n, 96
|
|
br label %loop
|
|
loop:
|
|
%i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
|
|
%i.next = add i32 %i, 96
|
|
%t = icmp ne i32 %i.next, %s
|
|
br i1 %t, label %loop, label %exit
|
|
exit:
|
|
ret void
|
|
|
|
; CHECK-LABEL: @test3
|
|
; CHECK: Loop %loop: backedge-taken count is ((-32 + (32 * %n)) /u 32)
|
|
; CHECK: Loop %loop: max backedge-taken count is 134217727
|
|
}
|
|
|
|
define void @test4(i32 %n) {
|
|
entry:
|
|
%s = mul i32 %n, 4
|
|
br label %loop
|
|
loop:
|
|
%i = phi i32 [ 0, %entry ], [ %i.next, %loop ]
|
|
%i.next = add i32 %i, 12
|
|
%t = icmp ne i32 %i.next, %s
|
|
br i1 %t, label %loop, label %exit
|
|
exit:
|
|
ret void
|
|
|
|
; CHECK-LABEL: @test4
|
|
; CHECK: Loop %loop: backedge-taken count is ((-4 + (-1431655764 * %n)) /u 4)
|
|
; CHECK: Loop %loop: max backedge-taken count is 1073741823
|
|
}
|
|
|
|
define void @test5(i32 %n) {
|
|
entry:
|
|
%s = mul i32 %n, 4
|
|
br label %loop
|
|
loop:
|
|
%i = phi i32 [ %s, %entry ], [ %i.next, %loop ]
|
|
%i.next = add i32 %i, -4
|
|
%t = icmp ne i32 %i.next, 0
|
|
br i1 %t, label %loop, label %exit
|
|
exit:
|
|
ret void
|
|
|
|
; CHECK-LABEL: @test5
|
|
; CHECK: Loop %loop: backedge-taken count is ((-4 + (4 * %n)) /u 4)
|
|
; CHECK: Loop %loop: max backedge-taken count is 1073741823
|
|
}
|