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llvm-mirror/test/CodeGen/MIR/X86/successor-basic-blocks.mir
Cong Hou 5d51a489ae Replace all weight-based interfaces in MBB with probability-based interfaces, and update all uses of old interfaces.
(This is the second attempt to submit this patch. The first caused two assertion
 failures and was reverted. See https://llvm.org/bugs/show_bug.cgi?id=25687)

The patch in http://reviews.llvm.org/D13745 is broken into four parts:

1. New interfaces without functional changes (http://reviews.llvm.org/D13908).
2. Use new interfaces in SelectionDAG, while in other passes treat probabilities
as weights (http://reviews.llvm.org/D14361).
3. Use new interfaces in all other passes.
4. Remove old interfaces.

This patch is 3+4 above. In this patch, MBB won't provide weight-based
interfaces any more, which are totally replaced by probability-based ones.
The interface addSuccessor() is redesigned so that the default probability is
unknown. We allow unknown probabilities but don't allow using it together
with known probabilities in successor list. That is to say, we either have a
list of successors with all known probabilities, or all unknown
probabilities. In the latter case, we assume each successor has 1/N
probability where N is the number of successors. An assertion checks if the
user is attempting to add a successor with the disallowed mixed use as stated
above. This can help us catch many misuses.

All uses of weight-based interfaces are now updated to use probability-based
ones.


Differential revision: http://reviews.llvm.org/D14973

llvm-svn: 254377
2015-12-01 05:29:22 +00:00

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# RUN: llc -march=x86-64 -start-after branch-folder -stop-after branch-folder -o /dev/null %s | FileCheck %s
# This test ensures that the MIR parser parses basic block successors correctly.
--- |
define i32 @foo(i32 %a) {
entry:
%0 = icmp sle i32 %a, 10
br i1 %0, label %less, label %exit
less:
ret i32 0
exit:
ret i32 %a
}
define i32 @bar(i32 %a) {
entry:
%b = icmp sle i32 %a, 10
br i1 %b, label %0, label %1
; <label>:0
ret i32 0
; <label>:1
ret i32 %a
}
...
---
name: foo
body: |
; CHECK-LABEL: bb.0.entry:
; CHECK: successors: %bb.1.less(0x40000000 / 0x80000000 = 50.00%), %bb.2.exit(0x40000000 / 0x80000000 = 50.00%)
; CHECK-LABEL: bb.1.less:
bb.0.entry:
successors: %bb.1.less, %bb.2.exit
liveins: %edi
CMP32ri8 %edi, 10, implicit-def %eflags
JG_1 %bb.2.exit, implicit killed %eflags
bb.1.less:
%eax = MOV32r0 implicit-def dead %eflags
RETQ killed %eax
bb.2.exit:
liveins: %edi
%eax = COPY killed %edi
RETQ killed %eax
...
---
name: bar
body: |
; CHECK-LABEL: name: bar
; Verify that we can have multiple lists of successors that will be merged
; into one.
; CHECK-LABEL: bb.0.entry:
; CHECK: successors: %bb.1(0x80000000 / 0x80000000 = 100.00%), %bb.2(0x00000000 / 0x80000000 = 0.00%)
bb.0.entry:
liveins: %edi
successors: %bb.1
successors: %bb.2
CMP32ri8 %edi, 10, implicit-def %eflags
JG_1 %bb.2, implicit killed %eflags
; Verify that we can have an empty list of successors.
; CHECK-LABEL: bb.1:
; CHECK-NEXT: %eax = MOV32r0 implicit-def dead %eflags
bb.1:
successors:
%eax = MOV32r0 implicit-def dead %eflags
RETQ killed %eax
bb.2:
liveins: %edi
%eax = COPY killed %edi
RETQ killed %eax
...