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llvm-project/llvm/test/Transforms/SimplifyCFG/PR16069.ll

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regenerate checks llvm-svn: 264677
2016-03-29 06:12:21 +08:00
; NOTE: Assertions have been autogenerated by update_test_checks.py
SimplifyCFG: Do not transform PHI to select if doing so would be unsafe PR16069 is an interesting case where an incoming value to a PHI is a trap value while also being a 'ConstantExpr'. We do not consider this case when performing the 'HoistThenElseCodeToIf' optimization. Instead, make our modifications more conservative if we detect that we cannot transform the PHI to a select. llvm-svn: 183152
2013-06-04 04:43:12 +08:00
; RUN: opt < %s -simplifycfg -S | FileCheck %s
@b = extern_weak global i32
Second part of pr16069 The problem this time seems to be a thinko. We were assuming that in the CFG A | \ | B | / C speculating the basic block B would cause only the phi value for the B->C edge to be speculated. That is not true, the phi's are semantically in the edges, so if the A->B->C path is taken, any code needed for A->C is not executed and we have to consider it too when deciding to speculate B. llvm-svn: 183226
2013-06-04 22:11:59 +08:00
SimplifyCFG: Do not transform PHI to select if doing so would be unsafe PR16069 is an interesting case where an incoming value to a PHI is a trap value while also being a 'ConstantExpr'. We do not consider this case when performing the 'HoistThenElseCodeToIf' optimization. Instead, make our modifications more conservative if we detect that we cannot transform the PHI to a select. llvm-svn: 183152
2013-06-04 04:43:12 +08:00
define i32 @foo(i1 %y) {
regenerate checks llvm-svn: 264677
2016-03-29 06:12:21 +08:00
; CHECK-LABEL: @foo(
; CHECK: [[COND_I:%.*]] = phi i32 [ srem (i32 1, i32 zext (i1 icmp eq (i32* @b, i32* null) to i32)), %bb2 ], [ 0, %0 ]
; CHECK-NEXT: ret i32 [[COND_I]]
;
SimplifyCFG: Do not transform PHI to select if doing so would be unsafe PR16069 is an interesting case where an incoming value to a PHI is a trap value while also being a 'ConstantExpr'. We do not consider this case when performing the 'HoistThenElseCodeToIf' optimization. Instead, make our modifications more conservative if we detect that we cannot transform the PHI to a select. llvm-svn: 183152
2013-06-04 04:43:12 +08:00
br i1 %y, label %bb1, label %bb2
bb1:
br label %bb3
bb2:
br label %bb3
bb3:
%cond.i = phi i32 [ 0, %bb1 ], [ srem (i32 1, i32 zext (i1 icmp eq (i32* @b, i32* null) to i32)), %bb2 ]
ret i32 %cond.i
}
Second part of pr16069 The problem this time seems to be a thinko. We were assuming that in the CFG A | \ | B | / C speculating the basic block B would cause only the phi value for the B->C edge to be speculated. That is not true, the phi's are semantically in the edges, so if the A->B->C path is taken, any code needed for A->C is not executed and we have to consider it too when deciding to speculate B. llvm-svn: 183226
2013-06-04 22:11:59 +08:00
define i32 @foo2(i1 %x) {
regenerate checks llvm-svn: 264677
2016-03-29 06:12:21 +08:00
; CHECK-LABEL: @foo2(
; CHECK: [[COND:%.*]] = phi i32 [ 0, %bb1 ], [ srem (i32 1, i32 zext (i1 icmp eq (i32* @b, i32* null) to i32)), %bb0 ]
; CHECK-NEXT: ret i32 [[COND]]
;
Second part of pr16069 The problem this time seems to be a thinko. We were assuming that in the CFG A | \ | B | / C speculating the basic block B would cause only the phi value for the B->C edge to be speculated. That is not true, the phi's are semantically in the edges, so if the A->B->C path is taken, any code needed for A->C is not executed and we have to consider it too when deciding to speculate B. llvm-svn: 183226
2013-06-04 22:11:59 +08:00
bb0:
br i1 %x, label %bb1, label %bb2
bb1:
br label %bb2
bb2:
%cond = phi i32 [ 0, %bb1 ], [ srem (i32 1, i32 zext (i1 icmp eq (i32* @b, i32* null) to i32)), %bb0 ]
ret i32 %cond
}