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98e3c40489
Tail merging can convert an undef use into a normal one when creating a common tail. Doing so can make the register live out from a block which previously contained the undef use. To keep the liveness up-to-date, insert IMPLICIT_DEFs in such blocks when necessary. To enable this patch the computeLiveIns() function which used to compute live-ins for a block and set them immediately is split into new functions: - computeLiveIns() just computes the live-ins in a LivePhysRegs set. - addLiveIns() applies the live-ins to a block live-in list. - computeAndAddLiveIns() is a convenience function combining the other two functions and behaving like computeLiveIns() before this patch. Based on a patch by Krzysztof Parzyszek <kparzysz@codeaurora.org> Differential Revision: https://reviews.llvm.org/D37034 llvm-svn: 312668
88 lines
2.1 KiB
YAML
88 lines
2.1 KiB
YAML
# RUN: llc -march=hexagon -run-pass branch-folder %s -o - -verify-machineinstrs | FileCheck %s
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# Branch folding will perform tail merging of bb.1 and bb.2, and bb.2 will
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# become the common tail. The use of R0 in bb.2 is <undef> while the
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# corresponding use in bb.1 is not. The common tail will have the <undef>
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# flag removed, which will cause R0 to become a live-in to bb.2. The problem
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# is that R0 is not live-out from all predecessors of bb.2, namely is not
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# live-out from bb.0. To remedy that, the branch folder should add an
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# IMPLICIT_DEF to that block.
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# CHECK-LABEL: name: func0
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# CHECK-LABEL: bb.0:
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# CHECK: %r0 = IMPLICIT_DEF
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# CHECK-LABEL: bb.1:
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# CHECK-LABEL: bb.2:
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# CHECK: liveins: %r0
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# CHECK: PS_storerhabs 0, %r0
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# CHECK: PS_jmpret
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---
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name: func0
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tracksRegLiveness: true
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body: |
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bb.0:
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liveins: %r31
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successors: %bb.1, %bb.2
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J2_jumpt undef %p0, %bb.2, implicit-def %pc
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J2_jump %bb.1, implicit-def %pc
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bb.1:
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liveins: %r31
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successors: %bb.3
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%r0 = L2_loadruh_io undef %r1, 0
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PS_storerhabs 0, killed %r0
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J2_jump %bb.3, implicit-def %pc
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bb.2:
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liveins: %r31
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successors: %bb.3
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PS_storerhabs 0, undef %r0
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J2_jump %bb.3, implicit-def %pc
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bb.3:
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liveins: %r31
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PS_jmpret killed %r31, implicit-def %pc
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...
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---
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# CHECK-LABEL: name: func1
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# CHECK-LABEL: bb.1:
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# CHECK: %r0 = IMPLICIT_DEF
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# CHECK-LABEL: bb.2:
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# CHECK-LABEL: bb.3:
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# CHECK: liveins: %r0
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# CHECK: PS_storerhabs 0, killed %r0
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# CHECK: PS_jmpret
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name: func1
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tracksRegLiveness: true
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body: |
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bb.0:
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liveins: %r31
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successors: %bb.1, %bb.2
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J2_jumpt undef %p0, %bb.2, implicit-def %pc
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J2_jump %bb.1, implicit-def %pc
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bb.1:
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liveins: %r31
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successors: %bb.3
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%r1 = A2_tfrsi 1
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PS_storerhabs 0, undef %r0
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%r0 = A2_tfrsi 1
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J2_jump %bb.3, implicit-def %pc
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bb.2:
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liveins: %r31
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successors: %bb.3
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%r0 = L2_loadruh_io undef %r1, 0
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PS_storerhabs 0, killed %r0
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%r0 = A2_tfrsi 1
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J2_jump %bb.3, implicit-def %pc
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bb.3:
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liveins: %r31
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PS_jmpret killed %r31, implicit undef %r0, implicit-def %pc
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...
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