Enhance BranchProbabilityInfo::calcUnreachableHeuristics for InvokeInst
This is recommit of r256028 with minor fixes in unittests:
CodeGen/Mips/eh.ll
CodeGen/Mips/insn-zero-size-bb.ll
Original commit message:
When identifying blocks post-dominated by an unreachable-terminated block
in BranchProbabilityInfo, consider only the edge to the normal destination
block if the terminator is InvokeInst and let calcInvokeHeuristics() decide
edge weights for the InvokeInst.
llvm-svn: 256202
diff --git a/llvm/lib/Analysis/BranchProbabilityInfo.cpp b/llvm/lib/Analysis/BranchProbabilityInfo.cpp
index 6cdf43a..a0d6123 100644
--- a/llvm/lib/Analysis/BranchProbabilityInfo.cpp
+++ b/llvm/lib/Analysis/BranchProbabilityInfo.cpp
@@ -147,6 +147,16 @@
if (TI->getNumSuccessors() == 1 || UnreachableEdges.empty())
return false;
+ // If the terminator is an InvokeInst, check only the normal destination block
+ // as the unwind edge of InvokeInst is also very unlikely taken.
+ if (auto *II = dyn_cast<InvokeInst>(TI))
+ if (PostDominatedByUnreachable.count(II->getNormalDest())) {
+ PostDominatedByUnreachable.insert(BB);
+ // Return false here so that edge weights for InvokeInst could be decided
+ // in calcInvokeHeuristics().
+ return false;
+ }
+
uint32_t UnreachableWeight =
std::max(UR_TAKEN_WEIGHT / (unsigned)UnreachableEdges.size(), MIN_WEIGHT);
for (SmallVectorImpl<unsigned>::iterator I = UnreachableEdges.begin(),
diff --git a/llvm/test/Analysis/BranchProbabilityInfo/noreturn.ll b/llvm/test/Analysis/BranchProbabilityInfo/noreturn.ll
index 6392637..513818d 100644
--- a/llvm/test/Analysis/BranchProbabilityInfo/noreturn.ll
+++ b/llvm/test/Analysis/BranchProbabilityInfo/noreturn.ll
@@ -77,3 +77,48 @@
exit:
ret i32 %b
}
+
+@_ZTIi = external global i8*
+
+; CHECK-LABEL: throwSmallException
+; CHECK-NOT: invoke i32 @smallFunction
+define i32 @throwSmallException(i32 %idx, i32 %limit) #0 personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
+entry:
+ %cmp = icmp sge i32 %idx, %limit
+ br i1 %cmp, label %if.then, label %if.end
+; CHECK: edge entry -> if.then probability is 0x00000800 / 0x80000000 = 0.00%
+; CHECK: edge entry -> if.end probability is 0x7ffff800 / 0x80000000 = 100.00% [HOT edge]
+
+if.then: ; preds = %entry
+ %exception = call i8* @__cxa_allocate_exception(i64 1) #0
+ invoke i32 @smallFunction(i32 %idx)
+ to label %invoke.cont unwind label %lpad
+; CHECK: edge if.then -> invoke.cont probability is 0x7ffff800 / 0x80000000 = 100.00% [HOT edge]
+; CHECK: edge if.then -> lpad probability is 0x00000800 / 0x80000000 = 0.00%
+
+invoke.cont: ; preds = %if.then
+ call void @__cxa_throw(i8* %exception, i8* bitcast (i8** @_ZTIi to i8*), i8* null) #1
+ unreachable
+
+lpad: ; preds = %if.then
+ %ll = landingpad { i8*, i32 }
+ cleanup
+ ret i32 %idx
+
+if.end: ; preds = %entry
+ ret i32 %idx
+}
+
+@a = global i32 4
+define i32 @smallFunction(i32 %a) {
+entry:
+ %r = load volatile i32, i32* @a
+ ret i32 %r
+}
+
+attributes #0 = { nounwind }
+attributes #1 = { noreturn }
+
+declare i8* @__cxa_allocate_exception(i64)
+declare i32 @__gxx_personality_v0(...)
+declare void @__cxa_throw(i8*, i8*, i8*)
diff --git a/llvm/test/CodeGen/Mips/eh.ll b/llvm/test/CodeGen/Mips/eh.ll
index 2f843d9..19f3d4d 100644
--- a/llvm/test/CodeGen/Mips/eh.ll
+++ b/llvm/test/CodeGen/Mips/eh.ll
@@ -24,7 +24,7 @@
lpad: ; preds = %entry
; CHECK-EL: # %lpad
-; CHECK-EL: bne $5
+; CHECK-EL: beq $5
%exn.val = landingpad { i8*, i32 }
cleanup
diff --git a/llvm/test/CodeGen/Mips/insn-zero-size-bb.ll b/llvm/test/CodeGen/Mips/insn-zero-size-bb.ll
index a9c2069..d2124c4 100644
--- a/llvm/test/CodeGen/Mips/insn-zero-size-bb.ll
+++ b/llvm/test/CodeGen/Mips/insn-zero-size-bb.ll
@@ -14,7 +14,7 @@
to label %unreachable unwind label %return
unreachable:
-; CHECK: ${{.*}}: # %unreachable
+; CHECK: {{.*}}: # %unreachable
; CHECK-NEXT: .insn
unreachable
diff --git a/llvm/test/CodeGen/X86/catchret-empty-fallthrough.ll b/llvm/test/CodeGen/X86/catchret-empty-fallthrough.ll
index 5405d57..7ad1033 100644
--- a/llvm/test/CodeGen/X86/catchret-empty-fallthrough.ll
+++ b/llvm/test/CodeGen/X86/catchret-empty-fallthrough.ll
@@ -34,12 +34,14 @@
; CHECK-LABEL: foo: # @foo
; CHECK: testb $1, %cl
-; CHECK: jne .LBB0_[[return:[0-9]+]]
+; CHECK: je .LBB0_[[try:[0-9]+]]
+; CHECK: .LBB0_[[return:[0-9]+]]:
+; CHECK: retq
+; CHECK: .LBB0_[[try]]:
; CHECK: .Ltmp0:
; CHECK: callq bar
; CHECK: .Ltmp1:
; CHECK: .LBB0_[[catch:[0-9]+]]:
-; CHECK: .LBB0_[[return]]:
; CHECK: .seh_handlerdata
; CHECK-NEXT: .Lfoo$parent_frame_offset = 32