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7f73476be8
When optimization is disabled, edge weights that are stored in MBB won't be used so that we don't have to store them. Currently, this is done by adding successors with default weight 0, and if all successors have default weights, the weight list will be empty. But that the weight list is empty doesn't mean disabled optimization (as is stated several times in MachineBasicBlock.cpp): it may also mean all successors just have default weights. We should discourage using default weights when adding successors, because it is very easy for users to forget update the correct edge weights instead of using default ones (one exception is that the MBB only has one successor). In order to detect such usages, it is better to differentiate using default weights from the case when optimizations is disabled. In this patch, a new interface addSuccessorWithoutWeight(MBB*) is created for when optimization is disabled. In this case, MBB will try to maintain an empty weight list, but it cannot guarantee this as for many uses of addSuccessor() whether optimization is disabled or not is not checked. But it can guarantee that if optimization is enabled, then the weight list always has the same size of the successor list. Differential revision: http://reviews.llvm.org/D13963 llvm-svn: 251429
84 lines
1.7 KiB
YAML
84 lines
1.7 KiB
YAML
# RUN: llc -march=x86-64 -start-after branch-folder -stop-after branch-folder -o /dev/null %s | FileCheck %s
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# This test ensures that the MIR parser parses basic block successors correctly.
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--- |
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define i32 @foo(i32 %a) {
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entry:
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%0 = icmp sle i32 %a, 10
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br i1 %0, label %less, label %exit
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less:
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ret i32 0
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exit:
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ret i32 %a
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}
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define i32 @bar(i32 %a) {
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entry:
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%b = icmp sle i32 %a, 10
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br i1 %b, label %0, label %1
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; <label>:0
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ret i32 0
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; <label>:1
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ret i32 %a
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}
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...
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---
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name: foo
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body: |
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; CHECK-LABEL: bb.0.entry:
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; CHECK: successors: %bb.1.less(0), %bb.2.exit(0)
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; CHECK-LABEL: bb.1.less:
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bb.0.entry:
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successors: %bb.1.less, %bb.2.exit
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liveins: %edi
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CMP32ri8 %edi, 10, implicit-def %eflags
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JG_1 %bb.2.exit, implicit killed %eflags
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bb.1.less:
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%eax = MOV32r0 implicit-def dead %eflags
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RETQ killed %eax
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bb.2.exit:
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liveins: %edi
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%eax = COPY killed %edi
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RETQ killed %eax
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...
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---
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name: bar
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body: |
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; CHECK-LABEL: name: bar
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; Verify that we can have multiple lists of successors that will be merged
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; into one.
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; CHECK-LABEL: bb.0.entry:
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; CHECK: successors: %bb.1(0), %bb.2(0)
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bb.0.entry:
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liveins: %edi
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successors: %bb.1
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successors: %bb.2
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CMP32ri8 %edi, 10, implicit-def %eflags
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JG_1 %bb.2, implicit killed %eflags
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; Verify that we can have an empty list of successors.
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; CHECK-LABEL: bb.1:
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; CHECK-NEXT: %eax = MOV32r0 implicit-def dead %eflags
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bb.1:
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successors:
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%eax = MOV32r0 implicit-def dead %eflags
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RETQ killed %eax
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bb.2:
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liveins: %edi
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%eax = COPY killed %edi
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RETQ killed %eax
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...
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