llvm-6502/test/Analysis/BranchProbabilityInfo/pr18705.ll
Akira Hatanaka 268c0509a9 Fix a bug in which BranchProbabilityInfo wasn't setting branch weights of basic blocks inside loops correctly.
Previously, BranchProbabilityInfo::calcLoopBranchHeuristics would determine the weights of basic blocks inside loops even when it didn't have enough information to estimate the branch probabilities correctly. This patch fixes the function to exit early if it doesn't see any exit edges or back edges and let the later heuristics determine the weights.

This fixes PR18705 and <rdar://problem/15991090>.

Differential Revision: http://reviews.llvm.org/D3363



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206194 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-14 16:56:19 +00:00

59 lines
2.2 KiB
LLVM

; RUN: opt < %s -analyze -branch-prob | FileCheck %s
; Since neither of while.body's out-edges is an exit or a back edge,
; calcLoopBranchHeuristics should return early without setting the weights.
; calcFloatingPointHeuristics, which is run later, sets the weights.
;
; CHECK: edge while.body -> if.then probability is 20 / 32 = 62.5%
; CHECK: edge while.body -> if.else probability is 12 / 32 = 37.5%
define void @foo1(i32 %n, i32* nocapture %b, i32* nocapture %c, i32* nocapture %d, float* nocapture readonly %f0, float* nocapture readonly %f1) {
entry:
%tobool8 = icmp eq i32 %n, 0
br i1 %tobool8, label %while.end, label %while.body.lr.ph
while.body.lr.ph:
%0 = sext i32 %n to i64
br label %while.body
while.body:
%indvars.iv = phi i64 [ %0, %while.body.lr.ph ], [ %indvars.iv.next, %if.end ]
%b.addr.011 = phi i32* [ %b, %while.body.lr.ph ], [ %b.addr.1, %if.end ]
%d.addr.010 = phi i32* [ %d, %while.body.lr.ph ], [ %incdec.ptr4, %if.end ]
%c.addr.09 = phi i32* [ %c, %while.body.lr.ph ], [ %c.addr.1, %if.end ]
%indvars.iv.next = add nsw i64 %indvars.iv, -1
%arrayidx = getelementptr inbounds float* %f0, i64 %indvars.iv.next
%1 = load float* %arrayidx, align 4
%arrayidx2 = getelementptr inbounds float* %f1, i64 %indvars.iv.next
%2 = load float* %arrayidx2, align 4
%cmp = fcmp une float %1, %2
br i1 %cmp, label %if.then, label %if.else
if.then:
%incdec.ptr = getelementptr inbounds i32* %b.addr.011, i64 1
%3 = load i32* %b.addr.011, align 4
%add = add nsw i32 %3, 12
store i32 %add, i32* %b.addr.011, align 4
br label %if.end
if.else:
%incdec.ptr3 = getelementptr inbounds i32* %c.addr.09, i64 1
%4 = load i32* %c.addr.09, align 4
%sub = add nsw i32 %4, -13
store i32 %sub, i32* %c.addr.09, align 4
br label %if.end
if.end:
%c.addr.1 = phi i32* [ %c.addr.09, %if.then ], [ %incdec.ptr3, %if.else ]
%b.addr.1 = phi i32* [ %incdec.ptr, %if.then ], [ %b.addr.011, %if.else ]
%incdec.ptr4 = getelementptr inbounds i32* %d.addr.010, i64 1
store i32 14, i32* %d.addr.010, align 4
%5 = trunc i64 %indvars.iv.next to i32
%tobool = icmp eq i32 %5, 0
br i1 %tobool, label %while.end, label %while.body
while.end:
ret void
}