Author: hans
Date: Thu Aug 29 05:37:46 2019
New Revision: 370344
URL: http://llvm.org/viewvc/llvm-project?rev=370344&view=rev
Log:
ReleaseNotes: sinking of instructions without uses
Modified:
llvm/branches/release_90/docs/ReleaseNotes.rst
Modified: llvm/branches/release_90/docs/ReleaseNotes.rst
URL:
http://llvm.org/viewvc/llvm-project/llvm/branches/release_90/docs/ReleaseNotes.rst?rev=370344&r1=370343&r2=370344&view=diff
==============================================================================
--- llvm/branches/release_90/docs/ReleaseNotes.rst (original)
+++ llvm/branches/release_90/docs/ReleaseNotes.rst Thu Aug 29 05:37:46 2019
@@ -115,6 +115,26 @@ Noteworthy optimizations
jmp qword ptr [8*rax + .LJTI0_0]
+* LLVM can now sink similar instructions to a common successor block also when
+ the instructions have no uses, such as calls to void functions. This allows
+ code such as
+
+ .. code-block:: c
+
+ void g(int);
+ enum e { A, B, C, D };
+ void f(e x, int y, int z) {
+ switch(x) {
+ case A: g(6); break;
+ case B: g(3); break;
+ case C: g(9); break;
+ case D: g(2); break;
+ }
+ }
+
+ to be optimized to a single call to ``g``, with the argument loaded from a
+ lookup table.
+
Changes to the LLVM IR
----------------------
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