// Remove the conditional branch from entry to the blocks.
BBI.NonPredSize -= TII->RemoveBranch(*BBI.BB);
- // Initialize liveins to the first BB. These are potentially redefined by
- // predicated instructions.
+ // Initialize the Redefs:
+ // - BB2 live-in regs need implicit uses before being redefined by BB1
+ // instructions.
+ // - BB1 live-out regs need implicit uses before being redefined by BB2
+ // instructions. We start with BB1 live-ins so we have the live-out regs
+ // after tracking the BB1 instructions.
Redefs.init(TRI);
Redefs.addLiveIns(*BBI1->BB);
+ Redefs.addLiveIns(*BBI2->BB);
// Remove the duplicated instructions at the beginnings of both paths.
// Skip dbg_value instructions
--- /dev/null
+# RUN: llc -march=hexagon -run-pass if-converter %s -o - | FileCheck %s
+
+# Make sure that the necessary implicit uses are added to predicated
+# instructions.
+
+# CHECK-LABEL: name: foo
+
+--- |
+ define void @foo() {
+ ret void
+ }
+...
+
+---
+name: foo
+tracksRegLiveness: true
+allVRegsAllocated: true
+body: |
+ bb.0:
+ successors: %bb.1, %bb.2
+ liveins: %r0, %r2, %p1
+ J2_jumpf %p1, %bb.1, implicit-def %pc
+ J2_jump %bb.2, implicit-def %pc
+ bb.1:
+ successors: %bb.3
+ liveins: %r2
+ %r0 = A2_tfrsi 2
+ J2_jump %bb.3, implicit-def %pc
+ bb.2:
+ successors: %bb.3
+ liveins: %r0
+ ; Even though r2 was not live on entry to this block, it was live across
+ ; block bb.1 in the original diamond. After if-conversion, the diamond
+ ; became a single block, and so r2 is now live on entry to the instructions
+ ; originating from bb.2.
+ ; CHECK: %r2 = C2_cmoveit %p1, 1, implicit %r2
+ %r2 = A2_tfrsi 1
+ bb.3:
+ liveins: %r0, %r2
+ %r0 = A2_add %r0, %r2
+ J2_jumpr %r31, implicit-def %pc
+...
+