Fix PR 4626, a crash in branch folding after OptimizeBlock

produced a CFG it wasn't prepared for.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78351 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/BranchFolding.cpp b/lib/CodeGen/BranchFolding.cpp
index 193bbb610f792065626009ae1a0d53593c8c3cd6..d25152b1e436ca5ccd62dd36d1267a48172b40ba 100644 (file)
--- a/lib/CodeGen/BranchFolding.cpp
+++ b/lib/CodeGen/BranchFolding.cpp
@@ -893,8 +893,24 @@ void BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
       while (!MBB->pred_empty()) {
         MachineBasicBlock *Pred = *(MBB->pred_end()-1);
         Pred->ReplaceUsesOfBlockWith(MBB, FallThrough);
+        // If this resulted in a predecessor with true and false edges
+        // both going to the fallthrough block, clean up; 
+        // BranchFolding doesn't like this.
+        MachineBasicBlock::succ_iterator SI = Pred->succ_begin();
+        bool found = false;
+        while (SI != Pred->succ_end()) {
+          if (*SI == FallThrough) {
+            if (!found) {
+              found = true;
+              ++SI;
+            } else {
+              SI = Pred->removeSuccessor(SI);
+            }
+          } else {
+            ++SI;
+          }
+        }
       }
-      
       // If MBB was the target of a jump table, update jump tables to go to the
       // fallthrough instead.
       MBB->getParent()->getJumpTableInfo()->

diff --git a/test/CodeGen/X86/2009-08-06-branchfolder-crash.ll b/test/CodeGen/X86/2009-08-06-branchfolder-crash.ll
new file mode 100644 (file)
index 0000000..5e58725
--- /dev/null
+++ b/test/CodeGen/X86/2009-08-06-branchfolder-crash.ll
@@ -0,0 +1,90 @@
+; RUN: llvm-as < %s | llc -O3
+; PR4626
+; ModuleID = '<stdin>'
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
+target triple = "i386-pc-linux-gnu"
+@g_3 = common global i8 0, align 1             ; <i8*> [#uses=2]
+
+define signext i8 @safe_mul_func_int16_t_s_s(i32 %_si1, i8 signext %_si2) nounwind readnone {
+entry:
+       %tobool = icmp eq i32 %_si1, 0          ; <i1> [#uses=1]
+       %cmp = icmp sgt i8 %_si2, 0             ; <i1> [#uses=2]
+       %or.cond = or i1 %cmp, %tobool          ; <i1> [#uses=1]
+       br i1 %or.cond, label %lor.rhs, label %land.lhs.true3
+
+land.lhs.true3:                ; preds = %entry
+       %conv5 = sext i8 %_si2 to i32           ; <i32> [#uses=1]
+       %cmp7 = icmp slt i32 %conv5, %_si1              ; <i1> [#uses=1]
+       br i1 %cmp7, label %cond.end, label %lor.rhs
+
+lor.rhs:               ; preds = %land.lhs.true3, %entry
+       %cmp10.not = icmp slt i32 %_si1, 1              ; <i1> [#uses=1]
+       %or.cond23 = and i1 %cmp, %cmp10.not            ; <i1> [#uses=1]
+       br i1 %or.cond23, label %lor.end, label %cond.false
+
+lor.end:               ; preds = %lor.rhs
+       %tobool19 = icmp ne i8 %_si2, 0         ; <i1> [#uses=2]
+       %lor.ext = zext i1 %tobool19 to i32             ; <i32> [#uses=1]
+       br i1 %tobool19, label %cond.end, label %cond.false
+
+cond.false:            ; preds = %lor.end, %lor.rhs
+       %conv21 = sext i8 %_si2 to i32          ; <i32> [#uses=1]
+       br label %cond.end
+
+cond.end:              ; preds = %cond.false, %lor.end, %land.lhs.true3
+       %cond = phi i32 [ %conv21, %cond.false ], [ 1, %land.lhs.true3 ], [ %lor.ext, %lor.end ]                ; <i32> [#uses=1]
+       %conv22 = trunc i32 %cond to i8         ; <i8> [#uses=1]
+       ret i8 %conv22
+}
+
+define i32 @func_34(i8 signext %p_35) nounwind readonly {
+entry:
+       %tobool = icmp eq i8 %p_35, 0           ; <i1> [#uses=1]
+       br i1 %tobool, label %lor.lhs.false, label %if.then
+
+lor.lhs.false:         ; preds = %entry
+       %tmp1 = load i8* @g_3           ; <i8> [#uses=1]
+       %tobool3 = icmp eq i8 %tmp1, 0          ; <i1> [#uses=1]
+       br i1 %tobool3, label %return, label %if.then
+
+if.then:               ; preds = %lor.lhs.false, %entry
+       %tmp4 = load i8* @g_3           ; <i8> [#uses=1]
+       %conv5 = sext i8 %tmp4 to i32           ; <i32> [#uses=1]
+       ret i32 %conv5
+
+return:                ; preds = %lor.lhs.false
+       ret i32 0
+}
+
+define void @foo(i32 %p_5) noreturn nounwind {
+entry:
+       %cmp = icmp sgt i32 %p_5, 0             ; <i1> [#uses=2]
+       %call = tail call i32 @safe() nounwind          ; <i32> [#uses=1]
+       %conv1 = trunc i32 %call to i8          ; <i8> [#uses=3]
+       %tobool.i = xor i1 %cmp, true           ; <i1> [#uses=3]
+       %cmp.i = icmp sgt i8 %conv1, 0          ; <i1> [#uses=3]
+       %or.cond.i = or i1 %cmp.i, %tobool.i            ; <i1> [#uses=1]
+       br i1 %or.cond.i, label %lor.rhs.i, label %land.lhs.true3.i
+
+land.lhs.true3.i:              ; preds = %entry
+       %xor = zext i1 %cmp to i32              ; <i32> [#uses=1]
+       %conv5.i = sext i8 %conv1 to i32                ; <i32> [#uses=1]
+       %cmp7.i = icmp slt i32 %conv5.i, %xor           ; <i1> [#uses=1]
+       %cmp7.i.not = xor i1 %cmp7.i, true              ; <i1> [#uses=1]
+       %or.cond23.i = and i1 %cmp.i, %tobool.i         ; <i1> [#uses=1]
+       %or.cond = and i1 %cmp7.i.not, %or.cond23.i             ; <i1> [#uses=1]
+       br i1 %or.cond, label %lor.end.i, label %for.inc
+
+lor.rhs.i:             ; preds = %entry
+       %or.cond23.i.old = and i1 %cmp.i, %tobool.i             ; <i1> [#uses=1]
+       br i1 %or.cond23.i.old, label %lor.end.i, label %for.inc
+
+lor.end.i:             ; preds = %lor.rhs.i, %land.lhs.true3.i
+       %tobool19.i = icmp eq i8 %conv1, 0              ; <i1> [#uses=0]
+       br label %for.inc
+
+for.inc:               ; preds = %for.inc, %lor.end.i, %lor.rhs.i, %land.lhs.true3.i
+       br label %for.inc
+}
+
+declare i32 @safe()