From eae7e7d00b9552546e9b105a4d7612713954f339 Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Thu, 20 Sep 2007 00:48:36 +0000
Subject: [PATCH] Fix optimization. %x = sub %x, %y does not imply that %y is
 zero.

llvm-svn: 42157
---
 .../Transforms/Scalar/PredicateSimplifier.cpp |   2 +-
 .../2007-09-19-Subtract.ll                    | 102 ++++++++++++++++++
 2 files changed, 103 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/Transforms/PredicateSimplifier/2007-09-19-Subtract.ll

diff --git a/llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp b/llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp
index 8b4ed73e47f6..3723bcbb0a6d 100644
--- a/llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp
+++ b/llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp
@@ -2001,7 +2001,7 @@ namespace {
               if (!isRelatedBy(Known, Zero, ICmpInst::ICMP_NE)) break;
               // otherwise, fall-through.
             case Instruction::Sub:
-              if (Unknown == Op1) break;
+              if (Unknown == Op0) break;
               // otherwise, fall-through.
             case Instruction::Xor:
             case Instruction::Add:
diff --git a/llvm/test/Transforms/PredicateSimplifier/2007-09-19-Subtract.ll b/llvm/test/Transforms/PredicateSimplifier/2007-09-19-Subtract.ll
new file mode 100644
index 000000000000..6c99b10942e1
--- /dev/null
+++ b/llvm/test/Transforms/PredicateSimplifier/2007-09-19-Subtract.ll
@@ -0,0 +1,102 @@
+; RUN: llvm-as < %s | opt -predsimplify | llvm-dis | grep -v unreachable
+; PR1683
+
+@.str = internal constant [13 x i8] c"c36174a.adb\00\00"		; <[13 x i8]*> [#uses=1]
+
+define void @_ada_c36174a() {
+entry:
+	%tmp3 = call i8* @llvm.stacksave( )		; <i8*> [#uses=1]
+	%tmp4 = invoke i32 @report__ident_int( i32 6 )
+			to label %invcont unwind label %entry.lpad_crit_edge		; <i32> [#uses=7]
+
+entry.lpad_crit_edge:		; preds = %entry
+	br label %lpad
+
+invcont:		; preds = %entry
+	%tmp6 = icmp slt i32 %tmp4, 1		; <i1> [#uses=1]
+	br i1 %tmp6, label %bb, label %bb9
+
+bb:		; preds = %invcont
+	invoke void @__gnat_rcheck_07( i8* getelementptr ([13 x i8]* @.str, i32 0, i32 0), i32 10 )
+			to label %invcont8 unwind label %bb.lpad_crit_edge
+
+bb.lpad_crit_edge:		; preds = %bb
+	br label %lpad
+
+invcont8:		; preds = %bb
+	unreachable
+
+bb9:		; preds = %invcont
+	%tmp51 = add i32 %tmp4, 6		; <i32> [#uses=2]
+	%tmp56 = icmp sgt i32 %tmp4, %tmp51		; <i1> [#uses=1]
+	br i1 %tmp56, label %bb9.bb76_crit_edge, label %bb9.bb61_crit_edge
+
+bb9.bb61_crit_edge:		; preds = %bb9
+	br label %bb61
+
+bb9.bb76_crit_edge:		; preds = %bb9
+	br label %bb76
+
+bb61:		; preds = %bb73, %bb9.bb61_crit_edge
+	%J4b.0 = phi i32 [ %tmp75, %bb73 ], [ %tmp4, %bb9.bb61_crit_edge ]		; <i32> [#uses=2]
+	%tmp70 = icmp eq i32 %tmp51, %J4b.0		; <i1> [#uses=1]
+	br i1 %tmp70, label %bb61.bb76_crit_edge, label %bb73
+
+bb61.bb76_crit_edge:		; preds = %bb61
+	br label %bb76
+
+bb73:		; preds = %bb61
+	%tmp75 = add i32 %J4b.0, 1		; <i32> [#uses=1]
+	br label %bb61
+
+bb76:		; preds = %bb61.bb76_crit_edge, %bb9.bb76_crit_edge
+	%tmp78 = icmp ne i32 %tmp4, 6		; <i1> [#uses=1]
+	%tmp81 = add i32 %tmp4, 6		; <i32> [#uses=1]
+	%tmp8182 = sext i32 %tmp81 to i64		; <i64> [#uses=1]
+	%tmp8384 = sext i32 %tmp4 to i64		; <i64> [#uses=1]
+	%tmp85 = sub i64 %tmp8182, %tmp8384		; <i64> [#uses=1]
+	%tmp86 = icmp ne i64 %tmp85, 6		; <i1> [#uses=1]
+	%tmp90 = or i1 %tmp78, %tmp86		; <i1> [#uses=1]
+	br i1 %tmp90, label %bb93, label %bb76.bb99_crit_edge
+
+bb76.bb99_crit_edge:		; preds = %bb76
+	br label %bb99
+
+bb93:		; preds = %bb76
+	invoke void @abort( )
+			to label %bb93.bb99_crit_edge unwind label %bb93.lpad_crit_edge
+
+bb93.lpad_crit_edge:		; preds = %bb93
+	br label %lpad
+
+bb93.bb99_crit_edge:		; preds = %bb93
+	br label %bb99
+
+bb99:		; preds = %bb93.bb99_crit_edge, %bb76.bb99_crit_edge
+	ret void
+
+lpad:		; preds = %bb93.lpad_crit_edge, %bb.lpad_crit_edge, %entry.lpad_crit_edge
+	%eh_ptr = call i8* @llvm.eh.exception( )		; <i8*> [#uses=2]
+	%eh_select102 = call i32 (i8*, i8*, ...)* @llvm.eh.selector.i32( i8* %eh_ptr, i8* bitcast (i32 (...)* @__gnat_eh_personality to i8*), i32 0 )		; <i32> [#uses=0]
+	call void @llvm.stackrestore( i8* %tmp3 )
+	call i32 (...)* @_Unwind_Resume( i8* %eh_ptr )		; <i32>:0 [#uses=0]
+	unreachable
+}
+
+declare i8* @llvm.stacksave()
+
+declare i32 @report__ident_int(i32)
+
+declare void @__gnat_rcheck_07(i8*, i32)
+
+declare void @abort()
+
+declare i8* @llvm.eh.exception()
+
+declare i32 @llvm.eh.selector.i32(i8*, i8*, ...)
+
+declare i32 @__gnat_eh_personality(...)
+
+declare i32 @_Unwind_Resume(...)
+
+declare void @llvm.stackrestore(i8*)