Subzero: Fix address mode optimization involving phi temporaries.

tests_lit/llvm2ice_tests/addr-opt-multi-def-var.ll

+; This is distilled from a real function that led to a bug in the
+; address mode optimization code.  It followed assignment chains
+; through non-SSA temporaries created from Phi instruction lowering.
+;
+; This test depends to some degree on the stability of "--verbose
+; addropt" output format.
+
+; RUN: %llvm2ice -O2 --verbose addropt %s | FileCheck %s
+
+declare i32 @_calloc_r(i32, i32, i32)
+
+define internal i32 @_Balloc(i32 %ptr, i32 %k) {
+entry:
+  %gep = add i32 %ptr, 76
+  %gep.asptr = inttoptr i32 %gep to i32*
+  %0 = load i32* %gep.asptr, align 1
+  %cmp = icmp eq i32 %0, 0
+  br i1 %cmp, label %if.then, label %if.end5
+
+if.then:                                          ; preds = %entry
+  %call = tail call i32 @_calloc_r(i32 %ptr, i32 4, i32 33)
+  %gep.asptr2 = inttoptr i32 %gep to i32*
+  store i32 %call, i32* %gep.asptr2, align 1
+  %cmp3 = icmp eq i32 %call, 0
+  br i1 %cmp3, label %return, label %if.end5
+
+if.end5:                                          ; preds = %if.then, %entry
+  %1 = phi i32 [ %call, %if.then ], [ %0, %entry ]
+  %gep_array = mul i32 %k, 4
+  %gep2 = add i32 %1, %gep_array
+  %gep2.asptr = inttoptr i32 %gep2 to i32*
+  %2 = load i32* %gep2.asptr, align 1
+; The above load instruction is a good target for address mode
+; optimization.  Correct analysis would lead to dump output like:
+;   Starting computeAddressOpt for instruction:
+;     [ 15]  %__13 = load i32* %gep2.asptr, align 1
+;   Instruction: [ 14]  %gep2.asptr = i32 %gep2
+;     results in Base=%gep2, Index=<null>, Shift=0, Offset=0
+;   Instruction: [ 13]  %gep2 = add i32 %__9, %gep_array
+;     results in Base=%__9, Index=%gep_array, Shift=0, Offset=0
+;   Instruction: [ 18]  %__9 = i32 %__9_phi
+;     results in Base=%__9_phi, Index=%gep_array, Shift=0, Offset=0
+;   Instruction: [ 12]  %gep_array = mul i32 %k, 4
+;     results in Base=%__9_phi, Index=%k, Shift=2, Offset=0
+;
+; Incorrect, overly-aggressive analysis would lead to output like:
+;   Starting computeAddressOpt for instruction:
+;     [ 15]  %__13 = load i32* %gep2.asptr, align 1
+;   Instruction: [ 14]  %gep2.asptr = i32 %gep2
+;     results in Base=%gep2, Index=<null>, Shift=0, Offset=0
+;   Instruction: [ 13]  %gep2 = add i32 %__9, %gep_array
+;     results in Base=%__9, Index=%gep_array, Shift=0, Offset=0
+;   Instruction: [ 18]  %__9 = i32 %__9_phi
+;     results in Base=%__9_phi, Index=%gep_array, Shift=0, Offset=0
+;   Instruction: [ 19]  %__9_phi = i32 %__4
+;     results in Base=%__4, Index=%gep_array, Shift=0, Offset=0
+;   Instruction: [ 12]  %gep_array = mul i32 %k, 4
+;     results in Base=%__4, Index=%k, Shift=2, Offset=0
+;
+; CHECK-NOT: results in Base=%__4,
+;
+  ret i32 %2
+
+return:                                           ; preds = %if.then
+  ret i32 0
+}