81 lines
3.4 KiB
Diff
81 lines
3.4 KiB
Diff
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Index: ghc-7.8.3/compiler/main/DriverPipeline.hs
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===================================================================
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--- ghc-7.8.3.orig/compiler/main/DriverPipeline.hs
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+++ ghc-7.8.3/compiler/main/DriverPipeline.hs
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@@ -1208,6 +1208,7 @@ runPhase (RealPhase (As with_cpp)) input
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as_prog <- whichAsProg
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let cmdline_include_paths = includePaths dflags
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+ let pic_c_flags = picCCOpts dflags
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next_phase <- maybeMergeStub
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output_fn <- phaseOutputFilename next_phase
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@@ -1221,6 +1222,9 @@ runPhase (RealPhase (As with_cpp)) input
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= liftIO $ as_prog dflags
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([ SysTools.Option ("-I" ++ p) | p <- cmdline_include_paths ]
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+ -- See Note [-fPIC for assembler]
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+ ++ map SysTools.Option pic_c_flags
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+
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-- We only support SparcV9 and better because V8 lacks an atomic CAS
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-- instruction so we have to make sure that the assembler accepts the
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-- instruction set. Note that the user can still override this
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@@ -1262,6 +1266,8 @@ runPhase (RealPhase SplitAs) _input_fn d
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osuf = objectSuf dflags
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split_odir = base_o ++ "_" ++ osuf ++ "_split"
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+ let pic_c_flags = picCCOpts dflags
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+
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-- this also creates the hierarchy
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liftIO $ createDirectoryIfMissing True split_odir
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@@ -1295,6 +1301,9 @@ runPhase (RealPhase SplitAs) _input_fn d
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then [SysTools.Option "-mcpu=v9"]
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else []) ++
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+ -- See Note [-fPIC for assembler]
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+ map SysTools.Option pic_c_flags ++
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+
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[ SysTools.Option "-c"
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, SysTools.Option "-o"
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, SysTools.FileOption "" (split_obj n)
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@@ -2210,3 +2219,38 @@ haveRtsOptsFlags dflags =
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isJust (rtsOpts dflags) || case rtsOptsEnabled dflags of
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RtsOptsSafeOnly -> False
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_ -> True
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+
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+-- Note [-fPIC for assembler]
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+-- When compiling .c source file GHC's driver pipeline basically
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+-- does the following two things:
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+-- 1. ${CC} -S 'PIC_CFLAGS' source.c
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+-- 2. ${CC} -x assembler -c 'PIC_CFLAGS' source.S
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+--
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+-- Why do we need to pass 'PIC_CFLAGS' both to C compiler and assembler?
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+-- Because on some architectures (at least sparc32) assembler also choses
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+-- relocation type!
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+-- Consider the following C module:
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+--
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+-- /* pic-sample.c */
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+-- int v;
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+-- void set_v (int n) { v = n; }
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+-- int get_v (void) { return v; }
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+--
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+-- $ gcc -S -fPIC pic-sample.c
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+-- $ gcc -c pic-sample.s -o pic-sample.no-pic.o # incorrect binary
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+-- $ gcc -c -fPIC pic-sample.s -o pic-sample.pic.o # correct binary
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+--
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+-- $ objdump -r -d pic-sample.pic.o > pic-sample.pic.o.od
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+-- $ objdump -r -d pic-sample.no-pic.o > pic-sample.no-pic.o.od
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+-- $ diff -u pic-sample.pic.o.od pic-sample.no-pic.o.od
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+--
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+-- Most of architectures won't show any difference in this test, but on sparc32
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+-- the following assembly snippet:
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+--
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+-- sethi %hi(_GLOBAL_OFFSET_TABLE_-8), %l7
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+--
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+-- generates two kinds or relocations, only 'R_SPARC_PC22' is correct:
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+--
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+-- 3c: 2f 00 00 00 sethi %hi(0), %l7
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+-- - 3c: R_SPARC_PC22 _GLOBAL_OFFSET_TABLE_-0x8
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+-- + 3c: R_SPARC_HI22 _GLOBAL_OFFSET_TABLE_-0x8
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