From: Evan Cheng <evan.cheng@apple.com>
Date: Thu, 17 Sep 2009 00:57:15 +0000 (+0000)
Subject: Fix PR4910: Broken logic in coalescer means when a physical register liveness is... 
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=5cf732e3b143df35fe2e956c73b60685fd5f0aeb;p=oota-llvm.git

Fix PR4910: Broken logic in coalescer means when a physical register liveness is being shortened, the sub-registers were not. The symptom is the register allocator could not find a free register for this particular test.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82108 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index 1288e3053aa..e90101a9ba5 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -547,14 +547,15 @@ static void removeRange(LiveInterval &li,
       if (!li_->hasInterval(*SR))
         continue;
       LiveInterval &sli = li_->getInterval(*SR);
+      MachineInstrIndex RemoveStart = Start;
       MachineInstrIndex RemoveEnd = Start;
       while (RemoveEnd != End) {
-        LiveInterval::iterator LR = sli.FindLiveRangeContaining(Start);
+        LiveInterval::iterator LR = sli.FindLiveRangeContaining(RemoveStart);
         if (LR == sli.end())
           break;
         RemoveEnd = (LR->end < End) ? LR->end : End;
-        sli.removeRange(Start, RemoveEnd, true);
-        Start = RemoveEnd;
+        sli.removeRange(RemoveStart, RemoveEnd, true);
+        RemoveStart = RemoveEnd;
       }
     }
   }
diff --git a/test/CodeGen/X86/2009-09-16-CoalescerBug.ll b/test/CodeGen/X86/2009-09-16-CoalescerBug.ll
new file mode 100644
index 00000000000..18b5a179c9e
--- /dev/null
+++ b/test/CodeGen/X86/2009-09-16-CoalescerBug.ll
@@ -0,0 +1,64 @@
+; RUN: llc < %s -mtriple=i386-apple-darwin10
+; PR4910
+
+%0 = type { i32, i32, i32, i32 }
+
+@boot_cpu_id = external global i32                ; <i32*> [#uses=1]
+@cpu_logical = common global i32 0, align 4       ; <i32*> [#uses=1]
+
+define void @topo_probe_0xb() nounwind ssp {
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.inc38, %entry
+  %0 = phi i32 [ 0, %entry ], [ %inc40, %for.inc38 ] ; <i32> [#uses=3]
+  %cmp = icmp slt i32 %0, 3                       ; <i1> [#uses=1]
+  br i1 %cmp, label %for.body, label %for.end41
+
+for.body:                                         ; preds = %for.cond
+  %1 = tail call %0 asm sideeffect "cpuid", "={ax},={bx},={cx},={dx},0,{cx},~{dirflag},~{fpsr},~{flags}"(i32 11, i32 %0) nounwind ; <%0> [#uses=3]
+  %asmresult.i = extractvalue %0 %1, 0            ; <i32> [#uses=1]
+  %asmresult10.i = extractvalue %0 %1, 2          ; <i32> [#uses=1]
+  %and = and i32 %asmresult.i, 31                 ; <i32> [#uses=2]
+  %shr42 = lshr i32 %asmresult10.i, 8             ; <i32> [#uses=1]
+  %and12 = and i32 %shr42, 255                    ; <i32> [#uses=2]
+  %cmp14 = icmp eq i32 %and12, 0                  ; <i1> [#uses=1]
+  br i1 %cmp14, label %for.end41, label %lor.lhs.false
+
+lor.lhs.false:                                    ; preds = %for.body
+  %asmresult9.i = extractvalue %0 %1, 1           ; <i32> [#uses=1]
+  %and7 = and i32 %asmresult9.i, 65535            ; <i32> [#uses=1]
+  %cmp16 = icmp eq i32 %and7, 0                   ; <i1> [#uses=1]
+  br i1 %cmp16, label %for.end41, label %for.cond17.preheader
+
+for.cond17.preheader:                             ; preds = %lor.lhs.false
+  %tmp24 = load i32* @boot_cpu_id                 ; <i32> [#uses=1]
+  %shr26 = ashr i32 %tmp24, %and                  ; <i32> [#uses=1]
+  br label %for.body20
+
+for.body20:                                       ; preds = %for.body20, %for.cond17.preheader
+  %2 = phi i32 [ 0, %for.cond17.preheader ], [ %inc32, %for.body20 ] ; <i32> [#uses=2]
+  %cnt.143 = phi i32 [ 0, %for.cond17.preheader ], [ %inc.cnt.1, %for.body20 ] ; <i32> [#uses=1]
+  %shr23 = ashr i32 %2, %and                      ; <i32> [#uses=1]
+  %cmp27 = icmp eq i32 %shr23, %shr26             ; <i1> [#uses=1]
+  %inc = zext i1 %cmp27 to i32                    ; <i32> [#uses=1]
+  %inc.cnt.1 = add i32 %inc, %cnt.143             ; <i32> [#uses=2]
+  %inc32 = add nsw i32 %2, 1                      ; <i32> [#uses=2]
+  %exitcond = icmp eq i32 %inc32, 255             ; <i1> [#uses=1]
+  br i1 %exitcond, label %for.end, label %for.body20
+
+for.end:                                          ; preds = %for.body20
+  %cmp34 = icmp eq i32 %and12, 1                  ; <i1> [#uses=1]
+  br i1 %cmp34, label %if.then35, label %for.inc38
+
+if.then35:                                        ; preds = %for.end
+  store i32 %inc.cnt.1, i32* @cpu_logical
+  br label %for.inc38
+
+for.inc38:                                        ; preds = %for.end, %if.then35
+  %inc40 = add nsw i32 %0, 1                      ; <i32> [#uses=1]
+  br label %for.cond
+
+for.end41:                                        ; preds = %lor.lhs.false, %for.body, %for.cond
+  ret void
+}