ee5585ed09
Improve and enable folding of conditional branches with tail calls. 1. Make it so that conditional tail calls can be emitted even when there are multiple predecessors. 2. Don't guard the transformation behind -Os. The rationale for guarding it was static-prediction can be affected by whether the branch is forward of backward. This is no longer true for almost any X86 cpus (anything newer than `SnB`) so is no longer a meaningful concern. Reviewed By: pengfei Differential Revision: https://reviews.llvm.org/D140931
191 lines
5.4 KiB
LLVM
191 lines
5.4 KiB
LLVM
; RUN: llc -opaque-pointers=0 -mtriple=x86_64-linux < %s | FileCheck %s
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; RUN: opt -opaque-pointers=0 -codegenprepare -S -mtriple=x86_64-linux < %s | FileCheck %s --check-prefix OPT
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; The exit block containing extractvalue can be duplicated into the BB
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; containing call. And later tail call can be generated.
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; CHECK-LABEL: test1:
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; CHECK: je foo # TAILCALL
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; CHECK: jmp bar # TAILCALL
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; OPT-LABEL: test1
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; OPT: if.then.i:
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; OPT-NEXT: tail call { i8*, i64 } @bar
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; OPT-NEXT: extractvalue
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; OPT-NEXT: bitcast
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; OPT-NEXT: ret
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;
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; OPT: if.end.i:
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; OPT-NEXT: tail call { i8*, i64 } @foo
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; OPT-NEXT: extractvalue
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; OPT-NEXT: bitcast
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; OPT-NEXT: ret
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define i64* @test1(i64 %size) {
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entry:
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%cmp.i.i = icmp ugt i64 %size, 16384
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%add.i.i = add i64 %size, 7
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%div.i.i = lshr i64 %add.i.i, 3
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%phitmp.i.i = trunc i64 %div.i.i to i32
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%cmp1.i = icmp eq i32 %phitmp.i.i, 0
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%cmp.i = or i1 %cmp.i.i, %cmp1.i
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br i1 %cmp.i, label %if.end.i, label %if.then.i
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if.then.i: ; preds = %entry
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%call1.i = tail call { i8*, i64 } @bar(i64 %size)
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br label %exit
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if.end.i: ; preds = %entry
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%call2.i = tail call { i8*, i64 } @foo(i64 %size)
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br label %exit
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exit:
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%call1.i.sink = phi { i8*, i64 } [ %call1.i, %if.then.i ], [ %call2.i, %if.end.i ]
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%ev = extractvalue { i8*, i64 } %call1.i.sink, 0
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%result = bitcast i8* %ev to i64*
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ret i64* %result
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}
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; The extractvalue extracts a field with non-zero offset, so the exit block
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; can't be duplicated.
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; CHECK-LABEL: test2:
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; CHECK: callq bar
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; CHECK: callq foo
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; OPT-LABEL: test2
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; OPT: if.then.i:
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; OPT-NEXT: tail call { i8*, i64 } @bar
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; OPT-NEXT: br label %exit
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;
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; OPT: if.end.i:
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; OPT-NEXT: tail call { i8*, i64 } @foo
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; OPT-NEXT: br label %exit
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;
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; OPT: exit:
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; OPT-NEXT: phi
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; OPT-NEXT: extractvalue
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; OPT-NEXT: ret
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define i64 @test2(i64 %size) {
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entry:
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%cmp.i.i = icmp ugt i64 %size, 16384
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%add.i.i = add i64 %size, 7
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%div.i.i = lshr i64 %add.i.i, 3
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%phitmp.i.i = trunc i64 %div.i.i to i32
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%cmp1.i = icmp eq i32 %phitmp.i.i, 0
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%cmp.i = or i1 %cmp.i.i, %cmp1.i
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br i1 %cmp.i, label %if.end.i, label %if.then.i
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if.then.i: ; preds = %entry
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%call1.i = tail call { i8*, i64 } @bar(i64 %size)
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br label %exit
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if.end.i: ; preds = %entry
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%call2.i = tail call { i8*, i64 } @foo(i64 %size)
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br label %exit
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exit:
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%call1.i.sink = phi { i8*, i64 } [ %call1.i, %if.then.i ], [ %call2.i, %if.end.i ]
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%ev = extractvalue { i8*, i64 } %call1.i.sink, 1
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ret i64 %ev
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}
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; The extractvalue accesses a nest struct type, the extracted field has zero
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; offset, so the exit block can still be duplicated, and tail call generated.
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; CHECK-LABEL: test3:
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; CHECK: je qux # TAILCALL
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; CHECK: jmp baz # TAILCALL
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; OPT-LABEL: test3
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; OPT: if.then.i:
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; OPT-NEXT: tail call { { i8*, i64 }, i64 } @baz
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; OPT-NEXT: extractvalue
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; OPT-NEXT: bitcast
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; OPT-NEXT: ret
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;
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; OPT: if.end.i:
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; OPT-NEXT: tail call { { i8*, i64 }, i64 } @qux
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; OPT-NEXT: extractvalue
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; OPT-NEXT: bitcast
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; OPT-NEXT: ret
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define i64* @test3(i64 %size) {
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entry:
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%cmp.i.i = icmp ugt i64 %size, 16384
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%add.i.i = add i64 %size, 7
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%div.i.i = lshr i64 %add.i.i, 3
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%phitmp.i.i = trunc i64 %div.i.i to i32
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%cmp1.i = icmp eq i32 %phitmp.i.i, 0
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%cmp.i = or i1 %cmp.i.i, %cmp1.i
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br i1 %cmp.i, label %if.end.i, label %if.then.i
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if.then.i: ; preds = %entry
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%call1.i = tail call { {i8*, i64}, i64 } @baz(i64 %size)
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br label %exit
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if.end.i: ; preds = %entry
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%call2.i = tail call { {i8*, i64}, i64 } @qux(i64 %size)
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br label %exit
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exit:
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%call1.i.sink = phi { {i8*, i64}, i64 } [ %call1.i, %if.then.i ], [ %call2.i, %if.end.i ]
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%ev = extractvalue { {i8*, i64}, i64 } %call1.i.sink, 0, 0
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%result = bitcast i8* %ev to i64*
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ret i64* %result
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}
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; The extractvalue accesses a nest struct with non-zero offset, so the exit
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; block can't be duplicated.
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; CHECK-LABEL: test4:
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; CHECK: callq baz
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; CHECK: callq qux
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; OPT-LABEL: test4
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; OPT: if.then.i:
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; OPT-NEXT: tail call { { i8*, i64 }, i64 } @baz
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; OPT-NEXT: br label %exit
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;
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; OPT: if.end.i:
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; OPT-NEXT: tail call { { i8*, i64 }, i64 } @qux
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; OPT-NEXT: br label %exit
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;
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; OPT: exit:
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; OPT-NEXT: phi
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; OPT-NEXT: extractvalue
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; OPT-NEXT: ret
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define i64 @test4(i64 %size) {
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entry:
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%cmp.i.i = icmp ugt i64 %size, 16384
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%add.i.i = add i64 %size, 7
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%div.i.i = lshr i64 %add.i.i, 3
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%phitmp.i.i = trunc i64 %div.i.i to i32
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%cmp1.i = icmp eq i32 %phitmp.i.i, 0
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%cmp.i = or i1 %cmp.i.i, %cmp1.i
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br i1 %cmp.i, label %if.end.i, label %if.then.i
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if.then.i: ; preds = %entry
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%call1.i = tail call { {i8*, i64}, i64 } @baz(i64 %size)
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br label %exit
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if.end.i: ; preds = %entry
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%call2.i = tail call { {i8*, i64}, i64 } @qux(i64 %size)
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br label %exit
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exit:
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%call1.i.sink = phi { {i8*, i64}, i64 } [ %call1.i, %if.then.i ], [ %call2.i, %if.end.i ]
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%ev = extractvalue { {i8*, i64}, i64 } %call1.i.sink, 0, 1
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ret i64 %ev
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}
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declare dso_local { i8*, i64 } @foo(i64)
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declare dso_local { i8*, i64 } @bar(i64)
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declare dso_local { {i8*, i64}, i64 } @baz(i64)
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declare dso_local { {i8*, i64}, i64 } @qux(i64)
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