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Revert the main portion of r31856. It was causing BranchFolding
to break up CFG diamonds by banishing one of the blocks to the end of the function, which is bad for code density and branch size. This does pessimize MultiSource/Benchmarks/Ptrdist/yacr2, the benchmark cited as the reason for the change, however I've examined the code and it looks more like a case of gaming a particular branch than of being generally applicable. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84803 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -945,15 +945,15 @@ bool BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
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}
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}
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// If this block doesn't fall through (e.g. it ends with an uncond branch or
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// has no successors) and if the pred falls through into this block, and if
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// it would otherwise fall through into the block after this, move this
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// block to the end of the function.
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// If this block has no successors (e.g. it is a return block or ends with
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// a call to a no-return function like abort or __cxa_throw) and if the pred
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// falls through into this block, and if it would otherwise fall through
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// into the block after this, move this block to the end of the function.
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//
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// We consider it more likely that execution will stay in the function (e.g.
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// due to loops) than it is to exit it. This asserts in loops etc, moving
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// the assert condition out of the loop body.
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if (!PriorCond.empty() && PriorFBB == 0 &&
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if (MBB->succ_empty() && !PriorCond.empty() && PriorFBB == 0 &&
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MachineFunction::iterator(PriorTBB) == FallThrough &&
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!CanFallThrough(MBB)) {
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bool DoTransform = true;
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@ -1,4 +1,4 @@
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; RUN: llc < %s -march=cellspu -o - | grep brz
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; RUN: llc < %s -march=cellspu -o - | grep brnz
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; PR3274
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target datalayout = "E-p:32:32:128-i1:8:128-i8:8:128-i16:16:128-i32:32:128-i64:32:128-f32:32:128-f64:64:128-v64:64:64-v128:128:128-a0:0:128-s0:128:128"
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@ -5,9 +5,9 @@
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; RUN: grep 1023 %t | count 1
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; RUN: grep 119 %t | count 1
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; RUN: grep JTI %t | count 2
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; RUN: grep jg %t | count 1
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; RUN: grep jg %t | count 3
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; RUN: grep ja %t | count 1
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; RUN: grep js %t | count 1
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; RUN: grep jns %t | count 1
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target triple = "i686-pc-linux-gnu"
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@ -74,16 +74,16 @@ exit:
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; CHECK: yet_more_involved:
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; CHECK: jmp .LBB3_1
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; CHECK-NEXT: align
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; CHECK-NEXT: .LBB3_7:
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; CHECK-NEXT: call block_a_true_func
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; CHECK-NEXT: jmp .LBB3_4
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; CHECK-NEXT: .LBB3_2:
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; CHECK-NEXT: .LBB3_3:
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; CHECK-NEXT: call bar99
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; CHECK-NEXT: call get
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; CHECK-NEXT: cmpl $2999, %eax
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; CHECK-NEXT: jle .LBB3_7
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; CHECK-NEXT: jg .LBB3_5
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; CHECK-NEXT: call block_a_true_func
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; CHECK-NEXT: jmp .LBB3_6
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; CHECK-NEXT: .LBB3_5:
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; CHECK-NEXT: call block_a_false_func
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; CHECK-NEXT: .LBB3_4:
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; CHECK-NEXT: .LBB3_6:
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; CHECK-NEXT: call block_a_merge_func
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; CHECK-NEXT: .LBB3_1:
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; CHECK-NEXT: call body
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