[PowerPC] eliminate unconditional branch to the next instruction
This patch makes analyzeBranch eliminate unconditional branch to the next instruction.
After basic blocks are re-organized by optimizers, such as machine block placement, a BB may end with an unconditional branch to the next (fallthrough) BB. This patch removes such redundant branch instruction.
Differential Revision: https://reviews.llvm.org/D37730
llvm-svn: 314297
diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
index 80530ec..1e4cc4a 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -494,6 +494,20 @@
if (!isUnpredicatedTerminator(*I))
return false;
+ if (AllowModify) {
+ // If the BB ends with an unconditional branch to the fallthrough BB,
+ // we eliminate the branch instruction.
+ if (I->getOpcode() == PPC::B &&
+ MBB.isLayoutSuccessor(I->getOperand(0).getMBB())) {
+ I->eraseFromParent();
+
+ // We update iterator after deleting the last branch.
+ I = MBB.getLastNonDebugInstr();
+ if (I == MBB.end() || !isUnpredicatedTerminator(*I))
+ return false;
+ }
+ }
+
// Get the last instruction in the block.
MachineInstr &LastInst = *I;
diff --git a/llvm/test/CodeGen/PowerPC/2016-04-28-setjmp.ll b/llvm/test/CodeGen/PowerPC/2016-04-28-setjmp.ll
index 09c0fa7..7f368f1 100644
--- a/llvm/test/CodeGen/PowerPC/2016-04-28-setjmp.ll
+++ b/llvm/test/CodeGen/PowerPC/2016-04-28-setjmp.ll
@@ -8,7 +8,7 @@
; EH_SjLj_Setup.
; CHECK: li 3, 1
-; CHECK-NEXT: b .+4
+; CHECK-NEXT: cmplwi 3, 0
define void @h() nounwind {
%1 = load i8**, i8*** bitcast (i8** @ptr to i8***), align 8
diff --git a/llvm/test/CodeGen/PowerPC/atomics-regression.ll b/llvm/test/CodeGen/PowerPC/atomics-regression.ll
index 0c7a31d..c8fb1e7 100644
--- a/llvm/test/CodeGen/PowerPC/atomics-regression.ll
+++ b/llvm/test/CodeGen/PowerPC/atomics-regression.ll
@@ -409,7 +409,6 @@
; PPC64LE-NEXT: .LBB40_1:
; PPC64LE-NEXT: stbcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB40_2
; PPC64LE-NEXT: .LBB40_2:
; PPC64LE-NEXT: lbarx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -472,7 +471,6 @@
; PPC64LE-NEXT: .LBB43_1:
; PPC64LE-NEXT: stbcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB43_2
; PPC64LE-NEXT: .LBB43_2:
; PPC64LE-NEXT: lbarx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -493,7 +491,6 @@
; PPC64LE-NEXT: .LBB44_1:
; PPC64LE-NEXT: stbcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB44_2
; PPC64LE-NEXT: .LBB44_2:
; PPC64LE-NEXT: lbarx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -623,7 +620,6 @@
; PPC64LE-NEXT: .LBB50_1:
; PPC64LE-NEXT: sthcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB50_2
; PPC64LE-NEXT: .LBB50_2:
; PPC64LE-NEXT: lharx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -686,7 +682,6 @@
; PPC64LE-NEXT: .LBB53_1:
; PPC64LE-NEXT: sthcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB53_2
; PPC64LE-NEXT: .LBB53_2:
; PPC64LE-NEXT: lharx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -707,7 +702,6 @@
; PPC64LE-NEXT: .LBB54_1:
; PPC64LE-NEXT: sthcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB54_2
; PPC64LE-NEXT: .LBB54_2:
; PPC64LE-NEXT: lharx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -837,7 +831,6 @@
; PPC64LE-NEXT: .LBB60_1:
; PPC64LE-NEXT: stwcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB60_2
; PPC64LE-NEXT: .LBB60_2:
; PPC64LE-NEXT: lwarx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -900,7 +893,6 @@
; PPC64LE-NEXT: .LBB63_1:
; PPC64LE-NEXT: stwcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB63_2
; PPC64LE-NEXT: .LBB63_2:
; PPC64LE-NEXT: lwarx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -921,7 +913,6 @@
; PPC64LE-NEXT: .LBB64_1:
; PPC64LE-NEXT: stwcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB64_2
; PPC64LE-NEXT: .LBB64_2:
; PPC64LE-NEXT: lwarx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -1051,7 +1042,6 @@
; PPC64LE-NEXT: .LBB70_1:
; PPC64LE-NEXT: stdcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB70_2
; PPC64LE-NEXT: .LBB70_2:
; PPC64LE-NEXT: ldarx 6, 0, 3
; PPC64LE-NEXT: cmpd 4, 6
@@ -1114,7 +1104,6 @@
; PPC64LE-NEXT: .LBB73_1:
; PPC64LE-NEXT: stdcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB73_2
; PPC64LE-NEXT: .LBB73_2:
; PPC64LE-NEXT: ldarx 6, 0, 3
; PPC64LE-NEXT: cmpd 4, 6
@@ -1135,7 +1124,6 @@
; PPC64LE-NEXT: .LBB74_1:
; PPC64LE-NEXT: stdcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB74_2
; PPC64LE-NEXT: .LBB74_2:
; PPC64LE-NEXT: ldarx 6, 0, 3
; PPC64LE-NEXT: cmpd 4, 6
@@ -1265,7 +1253,6 @@
; PPC64LE-NEXT: .LBB80_1:
; PPC64LE-NEXT: stbcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB80_2
; PPC64LE-NEXT: .LBB80_2:
; PPC64LE-NEXT: lbarx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -1328,7 +1315,6 @@
; PPC64LE-NEXT: .LBB83_1:
; PPC64LE-NEXT: stbcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB83_2
; PPC64LE-NEXT: .LBB83_2:
; PPC64LE-NEXT: lbarx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -1349,7 +1335,6 @@
; PPC64LE-NEXT: .LBB84_1:
; PPC64LE-NEXT: stbcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB84_2
; PPC64LE-NEXT: .LBB84_2:
; PPC64LE-NEXT: lbarx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -1479,7 +1464,6 @@
; PPC64LE-NEXT: .LBB90_1:
; PPC64LE-NEXT: sthcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB90_2
; PPC64LE-NEXT: .LBB90_2:
; PPC64LE-NEXT: lharx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -1542,7 +1526,6 @@
; PPC64LE-NEXT: .LBB93_1:
; PPC64LE-NEXT: sthcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB93_2
; PPC64LE-NEXT: .LBB93_2:
; PPC64LE-NEXT: lharx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -1563,7 +1546,6 @@
; PPC64LE-NEXT: .LBB94_1:
; PPC64LE-NEXT: sthcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB94_2
; PPC64LE-NEXT: .LBB94_2:
; PPC64LE-NEXT: lharx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -1693,7 +1675,6 @@
; PPC64LE-NEXT: .LBB100_1:
; PPC64LE-NEXT: stwcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB100_2
; PPC64LE-NEXT: .LBB100_2:
; PPC64LE-NEXT: lwarx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -1756,7 +1737,6 @@
; PPC64LE-NEXT: .LBB103_1:
; PPC64LE-NEXT: stwcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB103_2
; PPC64LE-NEXT: .LBB103_2:
; PPC64LE-NEXT: lwarx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -1777,7 +1757,6 @@
; PPC64LE-NEXT: .LBB104_1:
; PPC64LE-NEXT: stwcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB104_2
; PPC64LE-NEXT: .LBB104_2:
; PPC64LE-NEXT: lwarx 6, 0, 3
; PPC64LE-NEXT: cmpw 4, 6
@@ -1907,7 +1886,6 @@
; PPC64LE-NEXT: .LBB110_1:
; PPC64LE-NEXT: stdcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB110_2
; PPC64LE-NEXT: .LBB110_2:
; PPC64LE-NEXT: ldarx 6, 0, 3
; PPC64LE-NEXT: cmpd 4, 6
@@ -1970,7 +1948,6 @@
; PPC64LE-NEXT: .LBB113_1:
; PPC64LE-NEXT: stdcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB113_2
; PPC64LE-NEXT: .LBB113_2:
; PPC64LE-NEXT: ldarx 6, 0, 3
; PPC64LE-NEXT: cmpd 4, 6
@@ -1991,7 +1968,6 @@
; PPC64LE-NEXT: .LBB114_1:
; PPC64LE-NEXT: stdcx. 5, 0, 3
; PPC64LE-NEXT: beqlr 0
-; PPC64LE-NEXT: b .LBB114_2
; PPC64LE-NEXT: .LBB114_2:
; PPC64LE-NEXT: ldarx 6, 0, 3
; PPC64LE-NEXT: cmpd 4, 6
diff --git a/llvm/test/CodeGen/PowerPC/sjlj.ll b/llvm/test/CodeGen/PowerPC/sjlj.ll
index f86f534..984f9d9 100644
--- a/llvm/test/CodeGen/PowerPC/sjlj.ll
+++ b/llvm/test/CodeGen/PowerPC/sjlj.ll
@@ -77,7 +77,7 @@
; CHECK: bcl 20, 31, .LBB1_3
; CHECK: li 3, 1
; CHECK: #EH_SjLj_Setup .LBB1_3
-; CHECK: b .LBB1_1
+; CHECK: # BB#1:
; CHECK: .LBB1_3:
; CHECK: mflr [[REGL:[0-9]+]]